UNIVERSITY  OF  CALIFORNIA 
AT   LOS  ANGELES 


GIFT  OF 

CARNEGIE  INSTITUTION 
OF  WASHINGTON 


A  COMPARATIVE  STUDY  OF 

TEMPERATURE  FLUCTUATIONS  IN  DIFFERENT 

PARTS  OF  THE  HUMAN  BODY 


BY 


FRANCIS  G.  BENEDICT  AND  EDGAR  P.  SLACK 


(From  the  Nutrition  Laboratory  of  the  Carnegie  Institution  of  Washington} 


Q  r*     A  m  ~  WASHINGTON,  D.  C. 

PUBLISHED  BY  THE  CARNEGIE  INSTITUTION  OF  WASHINOTON 


1911 


A  COMPARATIVE  STUDY  OF 

TEMPERATURE  FLUCTUATIONS  IN  DIFFERENT 

PARTS  OF  THE  HUMAN  BODY 


BY 


FRANCIS  G.  BENEDICT  AND  EDGAR  P.  SLACK 


(From  the  Nutrition  Laboratory  of  the  Carnegie  Institution  of  Washington) 


WASHINGTON,  D.  C. 

PUBLISHED  BY  THE  CARNEGIE  INSTITUTION  OF  WASHINGTON 
191? 


CARNEGIE  INSTITUTION  OF  WASHINGTON 
PUBLICATION  No.  155 


PRESS  OF  GIBSON  BROTHERS 
WASHINGTON,  D.  C. 


W6 


CONTENTS. 


PART  I. 

PAGE. 

Introduction 1 

Heat  production 1 

Direct  and  indirect  calorimetry 3 

Purpose  of  the  research 3 

Localities  for  temperature  measurement 4 

Natural  cavities 4 

Artificial  cavities 6 

Surface  temperature 6 

Base  line  in  measuring  body-temperature 6 

Errors  in  rectal-temperature  measurement 6 

Constancy  of  rectal-temperature 7 

Factors  affecting  body-temperature 7 

PART  II. 

Methods  and  apparatus 9 

Comparison  of  methods 9 

Theory  of  method  of  measurement  used 11 

Adaptation  of  method  for  use 12 

Apparatus  used  in  the  research 12 

Constants  of  the  apparatus 12 

Construction  of  the  apparatus 14 

Measuring  instruments 14 

Thermal-junction  system 17 

Constant  temperature  oven 20 

Calibration  of  mercury  thermometers 22 

Method  of  operating  apparatus 23 

Calibration  of  thermal  junctions 24 

Computations  for  the  calibration 25 

A  sample  body-temperature  experiment 27 

Computations  for  the  experiment 27 

Precision  of  measurement 28 

Later  modification  of  the  apparatus 30 

PART  III. 

Discussion  of  results 35 

Thermal  gradient  of  the  body 35 

Method  of  studying  the  thermal  gradient 35 

Experimental  results ' 36 

General  conclusions  with  regard  to  the  thermal  gradient 39 

The  selection  of  localities  for  simultaneous  measurement  of  fluctuations  in  body- 
temperature  40 

Natural  cavities 40 

Temperature  measurements  in  the  mouth 40 

Artificial  cavities 43 

Simultaneous  observations  of  body-temperature  in  different  localities 44 

Experimental  results 45 

Conclusions , 72 


209173 


ILLUSTRATIONS. 


PAGE. 

Fig.     1.  Elementary  wiring  diagram  of  apparatus 11 

2.  Complete  wiring  diagram  of  apparatus 15 

3.  Types  of  thermal-junction  thermometers  used 18 

4.  Details  of  constant-temperature  bath 19 

5.  Constant-temperature  oven 21 

6.  Elementary  wiring  diagram  of  modified  apparatus 31 

7.  Complete  wiring  diagram  of  modified  apparatus 32 

8.  Detachable  thermometer  for  use  inside  the  calorimeter,  with  connections.  33 
9-13.  Observations  on  thermal  gradient 36-39 

14.  Observations  showing  rise  of  temperature  in  the  mouth 41 

15-38.  Temperature  curves  for  experiments 46-71 


A  COMPARATIVE  STUDY  OF  TEMPERATURE  FLUCTUATIONS  IN 
DIFFERENT  PARTS  OF  THE  HUMAN  BODY. 


PART  I. — INTRODUCTION. 

The  normal  body-temperature  is  a  resultant  of  two  factors,  thermogenesis, 
or  the  development  of  heat  inside  the  body;  and  thermolysis,  the  loss  of  heat 
from  the  body.  Usually  these  two  factors  are  so  delicately  adjusted  as  to  be 
nearly  equal  in  value  and  hence  the  resulting  temperature  of  the  body  does 
not  alter  materially.  When  there  are  marked  disturbances  in  either  factor, 
we  have  changes  in  body-temperature.  Innumerable  experiments1  have  been 
made  to  investigate  the  factors  influencing  both  thermogenesis  and  thermolysis, 
and  it  has  been  proved  that  the  most  important  factor  affecting  thermogenesis 
is  muscular  work,  either  voluntary  or  involuntary,  while  the  most  important 
factor  affecting  thermolysis  is  the  temperature  environment;  this  latter  is 
particularly  true  of  small  animals. 

A  knowledge  of  the  fluctuations  in  body-temperature  is  of  inestimable  value 
to  the  physician  as  an  index  of  the  body  condition;  in  health  the  normal  limits 
are  rarely  exceeded,  and  consequently  increased  temperature  indicates  that 
radical  measures  must  be  taken.  To  the  physiologist,  also,  a  knowledge  of  the 
course  of  the  normal  body-temperature  is  important,  and  when  experiments 
on  calorimetry  are  attempted  this  factor  has  especial  significance. 

HEAT  PRODUCTION. 

By  means  of  modern  apparatus,  an  accurate  measurement  may  now  be  made 
of  the  total  heat  given  off  from  the  body  of  a  man  during  an  experimental 
period  by  the  three  paths  of  conduction,  radiation,  and  the  latent  heat  of 
water  vaporized.  This  of  itself  is  an  important  contribution  to  physiology, 
but  of  still  greater  importance  is  the  measurement  of  the  total  heat  production. 
The  heat  production  may  or  may  not  be  the  same  as  the  heat  elimination, 
since  any  discrepancy  between  thermogenesis  and  thermolysis  causes  a  change 
in  body-temperature  resulting  in  the  loss  of  a  certain  amount  of  heat  previously 
stored,  or  the  storage  of  heat  to  be  subsequently  eliminated.  This  may  be 
shown  by  a  simple  calculation: 

From  the  results  of  a  large  number  of  experiments,  a  standard  value  for 
heat  production  has  been  computed  for  a  man  weighing  66.6  kilograms,  while 
at  rest  and  asleep.2  Owing  to  its  large  content  of  water,  the  body  has  the 


'A  historical  development  of  the  study  of  body-temperature,  including  methods,  is  given 
in  the  excellent  article  by  Pembrey  in  Schaefer's  Textbook  of  Physiology,  vol.  1,  1898,  p. 
785.  This  article  also  includes  an  extensive  statement  of  literature  up  to  the  date  of 
publication. 

"Benedict  and  Carpenter,  Pub.  No.  126,  Carnegie  Institution  of  Washington,  1910,  p.  253. 

1 


2  TEMPERATURE   FLUCTUATIONS   IN   THE   HUMAN    BODY. 

somewhat  high  specific  heat  of  approximately  0.83 ;'  the  body  of  a  man  weighing 
66.6  kilograms  would  consequently  have  a  hydrothermal  equivalent  of  about 
55  kilograms  of  water,  so  that  a  change  in  its  temperature  of  0.1°  C.  would  pro- 
duce either  a  storage  or  a  loss  of  5.5  calories  of  heat.  According  to  the  standard 
value  which  has  been  computed,  the  heat  production  of  a  man  of  this  weight 
and  under  these  conditions  would  be  71  calories;  consequently  the  amount  of 
heat  absorbed  or  given  up  by  the  body  as  a  result  of  the  change  in  temperature 
of  0.1°  C.,  i.  e.,  5.5  calories  per  hour,  would  be  approximately  7.7  per  cent  of 
the  total.  This  discrepancy  is  too  great  to  permit  the  measurement  of  the 
heat  elimination  to  be  taken  as  an  index  of  the  heat  production. 

Practical  experience  has  shown  that  a  change  in  temperature  amounting  to 
0.1°  C.  is  very  likely  to  occur,  even  with  enforced  body  quiet  and  rest;  as  a 
matter  of  fact,  a  normal  variation  in  temperature  amounting  to  1.5°  C.  is 
easily  possible  in  a  period  of  24  hours.  If,  as  is  wholly  unlikely,  such  a  large 
variation  as  1.5°  C.  should  take  place  in  a  shorter  experimental  period  as,  for 
instance,  1  hour,  there  would  be,  under  the  conditions  previously  cited,  a 
liberation  or  storage  of  heat  of  82.5  calories.  If  this  heat  were  stored  instead 
of  being  eliminated,  it  is  quite  conceivable  that  during  the  1-hour  period 
the  body  would  produce  heat  at  such  a  rate  as  to  raise  its  temperature  1.5°  C., 
with  the  elimination  of  absolutely  no  heat.  While  such  conditions  are  physio- 
logically impossible  in  so  short  a  period,  yet  when  physiologists  are  attempt- 
ing to  measure  the  heat  production  for  periods  of  1  hour  or  less  a  knowledge 
of  even  slight  variations  in  body-temperature  is  of  great  importance. 

The  determination  of  the  fluctuations  in  body-temperature  in  24-hour 
respiration  calorimeter  experiments  is  not  of  particular  importance,  since  one 
would  expect  to  find  approximately  the  same  body-temperature  at  approxi- 
mately the  same  hour  of  the  day;  thus,  all  of  the  earlier  experiments  published 
by  Atwater  and  Benedict2  were  planned  on  the  assumption  that  at  7  o'clock 
in  the  morning  (the  end  of  the  24-hour  period)  the  body  composition  of  a 
subject  existing  on  a  uniform  diet  was  constant  from  day  to  day,  and  the 
body-temperature  returned  to  essentially  the  same  level  at  this  time.  When 
the  attempt  is  made,  however,  to  shorten  the  experimental  periods  to  8  hours, 
6  hours,  2  hours,  or  even  less,  an  exact  knowledge  of  the  body-temperature 
at  the  beginning  and  end  of  each  period  becomes  of  more  and  more  importance. 
By  means  of  respiration  calorimeters,3  it  is  now  perfectly  feasible  to  measure 
the  chemical  factors  of  metabolism,  namely,  the  carbon  dioxide  excretion, 
oxygen  consumption,  and  water  vaporization,  in  periods  of  1  hour;  indeed,  in 
the  past  few  months,  experimental  periods  of  three-quarters  of  an  hour  have 
been  successfully  carried  out  and  made  a  part  of  the  regular  routine  of  this 
laboratory.  The  heat  eliminated  can  be  likewise  measured,  and  it  remains 
only  to  make  an  accurate  measurement  of  the  body-temperature  to  secure  the 
data  for  computing  with  considerable  exactness  the  heat  production  during 
these  periods. 

'Pembrey,  loc.  cit.,  p.  839. 

'Atwater  and  Benedict,  U.  S.  Dept.  Agri.,  Office  Exper.  Sta.,  Bull.  136.  1903. 

'Benedict,  Riche  and  Emmes,  Am.  Journ.  Physiol.,  1910,  26,  p.  1. 


INTRODUCTION.  3 

DIRECT  AND   INDIRECT   CALORIMETRY. 

The  data  regarding  the  heat  production  in  short  periods  are  especially 
valuable  in  demonstrating  the  accuracy  of  so-called  indirect  calorimetry  as 
compared  with  direct  calorimetry — a  demonstration  which  is  of  great  theo- 
retical as  well  as  practical  importance.  Such  a  comparison  has  been  repeatedly 
made  for  periods  of  24  hours1  by  Atwater  and  associates,  and  while  the  methods 
of  these  investigators  differ  somewhat  from  those  used  by  Zuntz,  it  has  been 
shown  conclusively  that  indirect  calorimetry  for  periods  of  this  length  is 
extremely  accurate.  This  demonstration,  however,  is  of  little  practical  value. 
In  the  first  place,  in  relatively  few  instances  is  the  total  carbon  dioxide  excre- 
tion for  24  hours  determined  from  which  the  heat  production  can  be  calculated. 
Secondly,  it  is  extremely  rare  that  the  total  oxygen  consumption  for  this  period 
is  determined.  Practically  all  of  the  computations  made  by  the  Zuntz  school 
have  been  based  upon  experiments  of  15  to  40  minutes'  duration.  It  becomes, 
therefore,  of  fundamental  importance  to  demonstrate  the  relationship  between 
the  gaseous  exchange  and  the  heat  production  not  only  in  periods  of  24  hours 
but  in  short  periods,  also. 

The  calculation  of  the  total  metabolism  from  the  data  regarding  the  nitro- 
gen excretion,  the  carbon-dioxide  excretion,  and  the  oxygen  consumption 
assumes  that  the  nitrogen  and  the  carbon  dioxide  excreted  and  the  oxygen 
consumed  during  a  given  period  represent  direct  molecular  transformations 
which  resulted  in  an  energy  transformation  during  that  period;  that  is,  that 
there  was  no  material  delay  in  the  oxidative  processes;  that  there  was  no 
accumulation  of  either  oxygen  or  carbon  dioxide  in  the  system;  and  that  the 
nitrogen  corresponded  to  the  protein  broken  down  during  the  period  under 
investigation.  Considerable  criticism  has  been  made  of  this  method  of  calcu- 
lation, but  in  all  probability,  if  proper  precautions  are  taken  to  secure  constant 
conditions  of  diet  for  a  sufficiently  long  period  beforehand,  there  will  be  a  gen- 
eral uniformity  in  metabolism :  and  while  the  metabolism  actually  measured 
in  any  hour  period,  as  for  instance,  between  8  and  9  a.  m.,  may  not  represent 
the  exact  transformation  during  the  period,  nevertheless  it  does  represent  a 
certain  definite  average  transformation  which  is  approximately  accurate. 
Until,  however,  it  has  been  clearly  demonstrated  that  indirect  and  direct 
calorimetry  agree  even  for  short  periods,  we  can  place  no  absolute  dependence 
upon  observations  and  calculations  based  upon  indirect  calorimetry. 

PURPOSE  OF  THE  RESEARCH. 

To  sum  up,  then,  it  is  possible  for  us  to  measure  with  great  accuracy  the 
carbon-dioxide  excretion,  oxygen  consumption,  water  vaporization,  and  nitro- 
gen excretion  during  any  given  experimental  period.  We  can  likewise  measure 
with  considerable  accuracy  the  heat  eliminated  by  radiation,  by  conduction; 
and  in  the  latent  heat  of  water  vaporized.  On  the  other  hand,  we  find  great 


'Atwater  and  Benedict,  loc.  cit.;  also  Benedict  and  Milner,  U.  S.  Dept.  Agri.,  Office  of 
Exper.  Sta.,  Bull.  175,  1907. 


4  TEMPERATURE   FLUCTUATIONS  IN   THE   HUMAN   BODY. 

difficulty  in  computing  exactly  the  heat  production,  since  this  is  dependent 
upon  an  accurate  measure  of  the  body-temperature.  In  any  method  of  meas- 
urement thus  far  devised,  the  important  assumption  must  be  made  that  the 
human  body  as  a  whole  undergoes  an  average  change  in  temperature  corre- 
sponding to  the  fluctuations  found  by  measuring  the  temperature  of  any  one 
portion  of  the  body.  This  last  assumption  has  been  based  on  such  uncertain 
evidence  up  to  the  present,  that  it  has  seemed  desirable  to  investigate  more 
carefully  the  fluctuations  in  temperature  of  the  different  parts  of  the  body. 

In  taking  up  this  problem,  we  were  at  once  confronted  with  two  rather 
important  questions:  First,  where  is  the  best  place  to  take  the  temperature  of 
the  body ;  and  second,  are  the  fluctuations  in  temperature  uniform  throughout 
the  body?  Certain  reasoning  might  here  be  brought  forward  to  prove  that 
the  blood,  being  a  great  distributor  of  heat,  equalizes  the  temperature  through- 
out the  whole  body,  so  that  we  should  expect  the  temperature  changes  in  the 
different  parts  to  follow  a  parallel  course.  If  all  parts  of  the  body  were  of 
essentially  the  same  temperature,  this  might  be  easily  assumed  without  ques- 
tion; as  a  matter  of  fact,  the  temperature  is  not  uniform,  there  being,  as  one 
would  naturally  expect,  a  sharp  thermal  gradient.  The  accurate  measurement 
of  the  surface  temperature  presents  many  difficulties,  but  as  a  result  of  num- 
erous observations  made  by  different  methods,  32°  C.  has  been  commonly 
accepted  as  a  standard,  and  is  probably  not  far  from  the  true  value.  The  tem- 
perature inside  the  body,  on  the  other  hand,  is  known  to  be  not  far  from  37°  C. ; 
we  have  here,  therefore,  a  gradient  of  5°  C.  This  gradient  should  be  very 
carefully  studied  before  assuming  that  the  temperature  in  different  parts  of 
the  body  remains  constant  throughout  the  whole  series  of  experiments.  If  the 
source  of  heat  is  constant,  as  evidenced  by  the  interior  temperature  of  the 
body,  and  the  temperature  of  the  environment  does  not  change,  there  is  every 
reason  for  believing  it  probable  that  the  gradient  will  be  constant. 

Accordingly,  in  this  particular  research  we  have  made  a  simultaneous  study 
of  body-temperature,  with  reference  to  determining:  (1)  the  best  place  for  an 
accurate  and  constant  measurement  of  body-temperature;  (2)  the  tempera- 
ture gradient  of  the  body;  and  especially  (3)  whether  or  not  the  temperature 
fluctuations  occurring  in  the  different  parts  of  the  body  are  uniform. 

LOCALITIES  FOR  TEMPERATURE  MEASUREMENT. 
NATURAL   CAVITIES. 

A  physical  examination  of  the  body  shows  that  there  are  a  number  of  natural 
cavities  which  provide  favorable  opportunity  for  measuring  the  body-tem- 
perature, since  they  are  surrounded  by  living  tissue  and  not  subjected  to  the 
immediate  effects  of  the  external  environmental  temperatures.  Of  these 
cavities,  by  common  consent  of  practically  all  physiologists,  the  rectum  is 
considered  to  be  the  most  favorable  and  to  indicate  the  truest  temperature  of 
the  interior  of  the  body.  Its  use,  however,  is  practicable  only  in  experiments 
with  patients  who  are  bed-ridden  and  in  physiological  tests.  With  female 


INTRODUCTION.  5 

subjects  under  similar  conditions,  the  vagina  is  also  an  admirable  place  for 
making  temperature  observations. 

Rectum. — In  taking  the  temperature  in  the  rectum,  it  is  of  prime  importance 
first  to  note  that  the  thermometer  should  not  be  imbedded  in  fecal  matter,  as 
otherwise  there  may  be  a  sluggishness  in  the  records.  This  is  particularly 
necessary  with  glass  clinical  thermometers,  which  are  sufficiently  rigid  to 
become  easily  imbedded  in  a  mass  of  fecal  matter.  Again,  the  thermometer 
must  be  inserted  deep  enough  in  the  rectum  to  make  sure  that  the  record  is 
not  affected  by  the  temperature  of  the  outside  air.  This  latter  point  will 
receive  special  consideration  later. 

Mouth. — In  the  private  practice  of  a  physician,  the  rectum  and  the  vagina 
are  practically  precluded  in  the  majority  of  instances  and  recourse  is  had  to 
taking  the  temperature  in  the  mouth.  While  it  is  true  that  the  cavity  in  the 
mouth  underneath  the  tongue  is  surrounded  by  living  tissue  and  protected, 
at  least  in  part,  from  the  external  environmental  temperature,  nevertheless 
the  cold  air  from  the  nasal  passages,  the  frequent  breathing  through  the  mouth, 
and  the  rapid  vaporization  of  water  by  the  relatively  dry  air  entering  the  mouth 
usually  produce  a  supercooling  of  this  cavity.  This  supercooling  may  be  very 
noticeable,  particularly  after  severe  exercise.1 

Stomach. — The  stomach  has  been  rarely  used  in  measuring  body-tempera- 
ture, since  it  is  somewhat  difficult  for  subjects  to  swallow  a  stomach  tube  with 
any  degree  of  comfort.  While  there  are  relatively  few  instances  in  which  a 
fistula  has  been  employed  for  such  measurements,  a  most  interesting  series  of 
observations  has  been  made  on  the  temperature  in  the  stomach  during  diges- 
tion, beginning  with  the  early  experiments  of  William  Beaumont2  on  Alexis 
St.  Martin,  and  continuing  with  the  more  recent  experiments  of  Rancken  and 
Tigerstedt.3  Under  ordinary  conditions,  however,  it  is  practically  impossible 
to  measure  the  temperature  in  this  way. 

Bladder. — So  far  as  we  know,  no  records  of  the  body-temperature  have  been 
taken  in  the  bladder  by  means  of  a  thermometer  inserted  through  a  catheter; 
nevertheless,  mention  should  be  made  of  the  extremely  ingenious  method  first 
suggested  by  Stephen  Hales4  of  measuring  the  temperature  of  freshly  voided 
urine  which  represents  very  nearly  the  temperature  of  the  interior  of  the  body. 
In  such  observations  it  is  evident  that  the  time  during  which  the  temperature 
can  be  taken  is  relatively  short,  depending  upon  the  volume  of  urine  passed. 
Furthermore,  the  thermometers  used  should  be  very  sensitive  and  should  first 
be  warmed  by  the  hand  or  in  the  mouth  to  nearly  the  temperature  of  the  body 
before  placing  the  bulb  in  the  stream  of  urine. 


'Williams  and  Arnold:  Phila.  Med.  Journ.,  3,  p.  1233. 

'Beaumont,  Experiments  and  observations  on  the  gastric  juice  and  the  physiology  of 
digestion,  Plattsburgh,  1833. 

'Rancken  and  Tigerstedt,  Biochem.  Zeitsch.,  1908,  11,  p.  36. 
'Hales,  Statical  Essays,  London,  1731,  2d  ed.,  1,  p.  59. 


6  TEMPERATURE   FLUCTUATIONS   IN   THE   HUMAN   BODY. 

ARTIFICIAL   CAVITIES. 

Axilla. — In  addition  to  the  natural  cavities  of  the  body,  there  are  certain 
artificial  cavities  which  can  be  formed  by  a  movement  of  the  limbs,  or  the 
folds  of  the  skin,  the  most  important  being  the  axilla.  In  the  normal  position 
of  the  arm,  the  axilla  provides  a  natural  cavity  which  needs  only  to  be  care- 
fully closed  in  order  to  approximate  an  interior  cavity  of  the  body.  The 
axilla  is,  however,  for  a  good  part  of  the  time  exposed  to  a  temperature  envi- 
ronment not  far  from  32°  C.,  i.  e.,  the  surface  temperature  of  the  body,  instead 
of  37°  C.,  that  of  the  interior  of  the  body.  The  presence  of  moisture,  sweat 
glands,  and  hair  all  combine  to  make  this  cavity  somewhat  difficult  to  use. 

Groin, — Another  locality  which  has  been  found  of  great  value  is  the  groin. 
Particularly  is  this  useful  in  taking  the  temperature  of  small  infants  when 
clinical  thermometers  can  not  be  used  in  either  the  mouth  or  the  rectum  for 
fear  of  breakage.  Unless  subjects  are  emaciated,  it  may  also  be  used  very 
satisfactorily  with  adults  after  the  cavity  has  become  warmed  to  the  tempera- 
ture of  the  body. 

Other  cavities. — Other  artificially  prepared  cavities  may  be  secured  by 
crossing  the  legs,  the  temperature  being  taken  inside  of  the  thighs;  and  by 
holding  the  thermometer  between  the  two  hands,  and  obtaining  the  tem- 
perature of  the  palms.  These  cavities,  however,  are  not  generally  used  for 
measuring  the  body-temperature  in  either  medical  practice  or  physiological 
experimenting. 

SURFACE   TEMPERATURE. 

The  temperature  of  the  exposed  surface  of  the  body  can  be  taken  at  any 
point,  but,  as  has  already  been  stated,  such  observations  present  many  diffi- 
culties. Any  form  of  thermometer  that  may  be  used  is  not  only  subject  to  the 
temperature  of  the  body,  but  also  to  that  of  the  cooler  outside  environment ; 
and  while  this  discrepancy  may  be  somewhat  lessened  by  artificial  warming, 
such  measures  are  at  best  unsatisfactory  and  inaccurate.  Again,  if  the  ther- 
mometer is  firmly  fastened  to  the  body,  there  is  liable  to  be  a  local  conges- 
tion, especially  if  the  area  of  the  thermometer  is  large,  and  the  functions 
of  the  sweat  glands,  both  underneath  the  thermometer  and  in  its  immediate 
vicinity,  may  be  somewhat  disturbed. 

BASE-LINE  IN  MEASURING  BODY-TEMPERATURE. 

An  examination  of  these  different  possibilities  or  localities  for  taking  the 
temperature  of  the  body  shows  immediately  that  those  least  affected  by 
environmental  changes  are  the  natural  cavities  in  the  body,  i.  e.,  the  rectum, 
the  vagina,  and  the  mouth,  the  records  obtained  in  the  rectum  being  commonly 
considered  the  best  suited  as  a  base-line  for  all  observations. 

ERRORS   IN   RECTAL-TEMPERATURE   MEASUREMENT. 

In  thus  using  the  rectal-temperature  as  the  base-line,  it  is  necessary  to  take 
into  consideration  the  possible  errors  affecting  the  measurements  made  in  the 


INTRODUCTION.  7 

rectum.  First,  as  has  already  been  pointed  out,  the  thermometer  should  not 
be  inserted  in  the  fecal  mass.  If  there  is  any  danger  of  this,  the  fecal  matter 
should  be  removed  by  a  water  enema;  also,  sufficient  time  should  elapse 
between  the  taking  of  the  enema  and  the  beginning  of  the  temperature  obser- 
vations to  make  sure  that  the  change  in  the  local  temperature  produced  by  the 
water  is  not  affecting  the  temperature  of  the  rectum.  Second,  the  thermometer 
must  be  inserted  sufficiently  deep  to  give  the  maximum  temperature,  the  depth 
required  being  readily  found  by  testing,  and  noting  the  point  at  which  the 
maximum  temperature  occurs.  If  the  thermometer  is  constructed  of  non- 
irritating  material,  there  is  very  little  liability  of  any  local  congestion.  The 
experience  of  observers  with  glass  mercurial  thermometers  has  led  to  some 
difficulty  in  securing  long-needed  observations  of  body-temperature,  owing 
to  the  rigid  construction  of  the  thermometers,  but  with  the  flexible  thermome- 
ter employed  by  Benedict  and  Snell1  continuous  observations  can  be  readily 
made  in  periods  of  several  days,  the  thermometer  being  removed  only  for 
defecation.  It  seems  well  established,  therefore,  that  with  a  proper  construc- 
tion of  the  thermometer  the  fear  of  local  congestion  may  be  entirely  eliminated. 

CONSTANCY   OF   RECTAL-TEMPERATURE. 

If  the  rectal-temperature  is  to  be  used  as  the  base-line,  it  is  natural  to  assume 
that  there  should  also  be  a  more  or  less  constant  temperature  which  should  be 
taken  as  the  base-line,  and  we  can  properly  question  whether  or  not  the  rectal- 
temperature  is  sufficiently  constant  for  this  purpose.  Obviously  the  tempera- 
tures which  are  markedly  above  the  average  of  a  large  number  of  observations 
may  be  taken  as  indicating  fever  and  should  not  be  used  as  a  base-line.  On  the 
other  hand,  there  may  be  a  fluctuation  in  the  normal  temperature  amounting 
to  1.5°  C.,  and  any  fluctuations  within  this  limit  may  be  reasonably  taken  as 
normal  for  the  individual  under  experimentation.  Before  assuming  that  the 
observations  of  the  rectal-temperature  represent  a  normal  value  for  the  indi- 
vidual, however,  we  should  examine  carefully  to  find  what  factors  affect  the 
body-temperature. 

FACTORS  AFFECTING  BODY-TEMPERATURE. 

Exposure  to  severe  cold  lowers  the  temperature,  provided  there  is  no  shiver- 
ing incidental  to  an  attempt  on  the  part  of  the  body  to  compensate  for  the 
excessive  heat  lost.  The  ingestion  of  hot  or  cold  food  and  drink,  likewise 
muscular  work,  produces  an  almost  immediate  effect.  In  connection  with 
muscular  work,  it  is  important  to  note  that  there  may  be  not  only  internal, 
but  also  external  muscular  work;  consequently,  for  the  strictest' comparison, 
the  temperature  of  the  subject  should  be  measured  under  constant  condi- 
tions of  muscular  activity,  ingestion  of  food,  etc. 

Furthermore,  it  has  long  been  known  among  physiologists  that  there  is  a 
rhythm  or  periodicity  in  the  temperature  of  the  body.  By  experiment,  it  has 

'Benedict  and  Snell,  Archiv  f.  d.  ges.  Physiol.,  1901,  88,  p.  492. 


8  TEMPERATURE   FLUCTUATIONS   IN   THE   HUMAN   BODY. 

been  found  that  this  rhythm  is  somewhat  as  follows :  The  minimum  tempera- 
ture occurs  during  the  early  morning  hours,  usually  between  2  and  5  o'clock; 
there  is  then  a  marked  early  morning  rise  which  becomes  less  pronounced  as 
the  day  progresses,  but  reaches  its  maximum  in  the  afternoon  about  5  o'clock; 
this  is  followed  by  a  slight  fall,  which  becomes  very  noticeable  after  retiring 
and  gradually  continues  until  the  minimum  point  is  again  reached  in  the 
early  morning. 

A  number  of  attempts  have  been  made  to  explain  this  rhythm,  which  as  yet 
have  been  only  partially  successful,  although  the  rhythm  appears  to  be  more 
or  less  coincident  with  the  muscular  activity  incidental  to  the  day's  work. 
This  explanation  is  not  scientifically  complete,  however,  for  it  does  not  explain 
why  a  night  watchman,1  who  for  seven  years  had  been  working  during  the 
night  and  sleeping  in  the  daytime,  should  still  have  the  highest  body-tempera- 
ture at  4  or  5  o'clock  in  the  afternoon  when  he  was  sound  asleep,  and  the 
lowest  value  at  4  or  5  o'clock  in  the  morning  when  he  was  awake  and  on  his 
rounds.  Daylight  and  cosmic  influences  have  also  been  thought  to  have  an 
effect  upon  this  rhythm.  It  is  not  the  object  of  this  report,  however,  to  enter 
into  a  discussion  of  the  cause  of  the  normal  periodicity  or  rhythm,  but  in 
any  study  of  body-temperature  this  factor  should  be  taken  into  consideration 
when  endeavoring  to  establish  a  base-line.  For  the  particular  reason  for  which 
this  investigation  was  undertaken,  namely,  to  study  simultaneously  the  tem- 
perature fluctuations  in  different  parts  of  the  body  in  order  to  find  whether  or 
not  they  paralleled  each  other,  the  absolute  temperature  values  at  any  given 
point  are  not  of  such  great  importance  as  are  the  variations.  Consequently 
we  may  assume  that  previous  experiments  have  demonstrated  clearly  the 
existence  of  a  rhythm  and  have  likewise  demonstrated  the  difficulty  of  giving 
a  satisfactory  explanation  which  covers  all  observations  thus  far  made. 

Johansson's  belief2  that  the  body-temperature  is  influenced  in  large  part  by 
the  metabolism  is  strongly  substantiated  by  his  observations,  and  yet  it  is 
difficult  to  conceive  that  the  night  watchman  previously  referred  to  had  a 
higher  metabolism  during  the  periods  when  he  was  sound  asleep  than  when  he 
was  sitting  up  in  a  chair  engaged  in  conversation.  From  the  well-known 
relationship  between  the  pulse-rate  and  the  metabolism,  it  is  clear  that  all 
future  experiments  on  body-temperature  should  be  accompanied  by  a  simul- 
taneous observation  of  the  pulse-rate  and,  so  far  as  possible,  of  the  metabolism 
and  its  changes.  In  the  majority  of  experiments,  observations  of  the  metab- 
olism will  be  impossible,  but  records  of  the  pulse-rate  may  be  easily  obtained 
by  practically  all  observers.  If  to  these  observations  can  be  added  others  with 
regard  to  the  blood  pressure  and  pulse  pressure,  the  results  will  be  still  more 
valuable,  especially  in  throwing  light  upon  the  contention  of  Johansson  that 
the  body-temperature  is  a  function  of  the  total  metabolism. 

'Benedict,  Am.  Journ.  Physiol.,  1904,  11,  p.  145. 
'Johansson,  Skand.  Archiv  f.  Physiol.,  1896,  7,  p.  123. 


METHODS   AND   APPARATUS.  9 

PART  II. — METHODS  AND  APPARATUS. 

An  analysis  of  the  measurements  to  be  made  as  outlined  in  the  preceding 
section  shows  that  the  method  of  measurement  must  comply  with  the  following 
requirements : 

Several  temperatures  must  be  observed  at  practically  the  same  time,  and 
this  process  repeated  at  intervals  of  a  few  minutes  for  protracted  periods. 

The  precision  of  the  measurement  must  approximate  0.01°  C. 

The  thermometers  must  be  capable  of  being  read  without  being  disturbed; 
they  must  also  be  small  and  flexible,  so  as  not  to  cause  undue  discomfort  even 
if  in  position  for  a  considerable  length  of  time. 

Only  two  methods  were  considered  as  being  able  to  meet  these  conditions, 
namely,  those  employing  (1)  electrical  resistance  thermometers,1  and  (2) 
electrical  thermal-junction  thermometers.2 

COMPARISON  OF  METHODS. 

The  many  advantages  of  the  resistance  method  have  led  to  its  extended 
application.  In  the  first  place,  it  has  inherently  a  greater  sensitiveness  than 
can  be  obtained  by  the  thermal-junction  method.  The  reason  for  this  might 
be  suggested  by  the  fact  that  in  the  resistance  method  the  amount  of  energy 
expended  in  the  thermometer  is  left  entirely  to  the  discretion  of  the  designer, 
while  in  the  thermal-junction  method  the  source  of  energy  is  in  the  thermome- 
ter itself  and  therefore  is  limited  by  the  physical  properties  of  the  junction. 
This  implies,  also,  that  the  e'ectromotive  forces  involved  in  the  resistance 
method  will,  in  general,  be  far  greater  than  those  used  in  measurement  with 
the  thermal  junction,  so  that  with  the  resistance  method  comparatively  little 
trouble  will  be  experienced  from  extraneous  electromotive  forces,  which  are  so 
common  a  source  of  annoyance  in  thermo-electric  measurements.  Another 
advantage  of  the  resistance  method  is  that  the  measurement  is  completed  by 
performing  a  single  operation,  usually  that  of  balancing  a  bridge;  there  is  no 
second  temperature  to  be  read,  no  potentiometer  current  to  be  adjusted,  and 
no  routine  observations  necessary  to  correct  for  the  effect  of  extraneous 
electromotive  forces.  Also,  the  apparatus  for  measuring  the  temperature  of 
the  resistance  thermometer  is  simpler  than  that  required  for  the  thermal 
junction,  as  in  the  former  case  no  constant  temperature  need  be  maintained, 
also  no  standard  cell  is  necessary. 

In  spite  of  these  manifest  advantages,  there  are  certain  qualities  inherent 
in  the  resistance  method  which  make  it  less  fitted  than  the  thermal-junction 
method  for  meeting  the  requirements  previously  outlined.  For  example,  the 
measuring  current  flowing  through  the  resistance  thermometer  produces  an 
appreciable  heating  of  the  wire,  the  resistance  of  which  is  being  measured. 
In  measurements  with  the  thermal  junction,  however,  the  current  taken  from 

'Benedict  and  Snell,  Archiv  f.  d.  ges.  Physiol.,  1901,  88,  p.  492;  and  1902,  90,  p.  33. 
:Gamgee,  Phil.  Trans.  Royal  Soc.  of  London,  Ser.  B.,  1908,  200,  p.  219. 


10  TEMPERATUKE    FLUCTUATIONS   IN    THE   HUMAN    BODY. 

he  junction  for  the  purpose  of  deflecting  a  galvanometer  would  be  very  slight, 
so  that  the  heating — which  depends  on  the  square  of  the  current— would  be 
very  small  indeed.  Furthermore,  a  method  may  be  used  which  does  not 
involve  drawing  current  from  the  junction,  and  thus  the  error  may  be  entirely 
avoided. 

Again,  the  resistance  thermometer,  as  usually  constructed  for  body-tem- 
perature measurement,  consists  of  a  coil  of  fine  wire,  inclosed  in  a  metal  shell. 
This  construction  is  necessarily  bulky,  owing  to  the  fact  that  a  considerable 
quantity  of  wire  must  be  used.  Moreover,  the  mass  of  the  thermometer  is 
large,  giving  more  or  less  lag,  and  its  construction  is  relatively  very  difficult. 
The  thermal-junction  thermometer,  on  the  other  hand,  in  its  simplest  but 
thoroughly  practical  form,  consists  merely  of  a  twisted  and  soldered  joint 
between  two  fine  wires,  one  of  which  is  insulated,  both  wires  being  protected 
from  moisture  and  mechanical  injury  by  an  outside  case  of  thin-walled  rubber 
tubing.  It  will  thus  be  seen  that  the  thermometer  is  small  and  flexible,  which 
not  only  permits  its  ready  introduction  into  the  deep  natural  cavities  of  the 
body,  but  also  allows  it  to  be  covered  easily  by  flesh  when  used  in  the  shallow 
artificial  cavities;  furthermore,  its  small  mass  precludes  any  appreciable  lag. 

A  third  disadvantage  of  the  resistance  method  is  that,  in  the  type  of  ther- 
mometer commonly  used  for  body-temperature  measurement,  the  resistance 
itself  is  not  in  very  good  thermal  contact  with  the  body  whose  temperature  is 
being  taken,  whereas  the  thermal  connection  between  the  thermal-junction 
thermometer  and  the  body  may  be  made  absolutely  ideal.  Since  no  theo- 
retical demands  will  be  violated  if  one  of  the  metals  of  the  junction  actually 
touches  the  body  being  measured,  the  junction  may  be  made  in  the  form  of  a 
wire  of  one  of  the  metals  soldered  to  the  back  of  a  thin  plate  or  cap  of  the 
other  and  the  face  of  this  latter  applied  directly  to  the  body ;  in  this  way  the 
active  material  of  the  thermometer  may  touch  the  body  without  even  the 
thinnest  layer  of  isolating  material. 

A  careful  comparison  of  the  advantages  and  disadvantages  of  these  two 
methods,  considered  only  in  the  light  of  the  requirements  of  these  special 
experiments  and  not  at  all  with  regard  to  temperature  measurements  in  general, 
led  to  the  adoption  of  the  thermal-junction  method,  and  this  in  spite  of  our 
previous  extended  use  of  the  resistance  thermometer  for  body-temperature 
measurements.  The  sensitiveness  was  considered  ample,  and  the  disadvan- 
tages of  the  occasional  observations  necessary  in  reading  a  second  temperature, 
balancing  current,  and  correcting  for  stray  voltage  were  regarded  as  being 
more  than  offset  by  the  freedom  from  heating  and  the  ability  to  use  ther- 
mometers which  were  at  once  small,  simple,  flexible,  and  strong.  The  thermal- 
junction  method  has  the  still  further  advantage  that  the  thermometers  are 
practically  interchangeable  without  adjustment. 


METHODS   AND   APPARATUS.  11 

THEORY  OF  METHOD  OF  MEASUREMENT  USED. 

The  thermal-junction  method  is  based  upon  the  well-known  principle  that 
if  a  junction  of  two  dissimilar  metals  be  heated,  a  difference  of  potential 
between  the  two  will  result;  and  if  the  circuit  be  closed  through  a  galvanom- 
eter, a  current  will  be  produced  and  the  galvanometer  deflected.  In  order 
that  small  temperature  fluctuations  may  be  measured  with  precision,  use  is 
made  of  a  second  junction  in  series  with  and  opposed  to  the  first,  this  second 
junction  being  kept  at  a  constant  known  temperature  somewhere  in  the  region 
of  the  temperature  to  be  measured.  By  this  means  the  net  electromotive  force 
is  made  very  small,  so  that  slight  changes  due  to  fluctuations  of  the  unknown 
temperature  form  a  large  percentage  of  the  whole.  The  use  of  deflections  in 
this  way,  although  convenient  and  simple,  has  one  disadvantage,  in  that  the 
resistance  of  the  galvanometer  and  conducting  wires  must  be  taken  into 
account,  since  a  change  in  the  circuit  resistance  would  cause  an  inversely  pro- 
portional change  in  the  deflection.  With  the  appa- 
ratus used  in  these  body-temperature  experiments, 
a  fluctuation  of  more  than  1.2°  C.  in  the  galvan- 
ometer temperature  would  not  have  been  allowable. 
Moreover,  the  effective  voltage  at  the  galvanometer 
terminals,  being  the  voltage  of  the  thermal-junction 
system  minus  the  fall  in  potential  along  the  wires, 
would  have  been  reduced  to  about  75  per  cent  of 
its  total  value. 

These  conditions,  although  not  prohibitive,  were 
nevertheless  regarded    as    undesirable,   so   that   a     FIG.  i.  Elementary  wiring  dia- 

.,.,.,  .11,  ,•        i  •    i        i  gram  of  apparatus.    Current 

null     method,  by  means  of  which  they  were  en-          from  the  battery  B  flows 

A.      ,                                                  r-        11           i       •  i      i  ™  •  through  the  slide  wire    DC 

tirely     avoided,     Was     finally     decided     Upon.  ThlS  and   returns  to  the  battery 

..,,            ..              ..              ii-                       T/.          •  c      ,  through     the     ammeter    A. 

null       Or       Zero       method   IS   a    modification  Of  the  The  thermal-junction  system 

,.  ,        ,.  . ,        ,      .          .,  TT,  with  the  galvanometer 

ordinary  potentiometer  method   for  the  measure-          G,  is  connected  at  one  end  to 

*   ,  ...  .      ,      ,  C,  and    at  the  other    to  a 

ment  of  electromotive  forces,  and  consists  in  balanc-          movable  contact  which  may 

,.  .  cii  i   •  •  be  touched  at  any  point  along 

ing  the  electromotive  force  of  the  thermal-junction          the  slide  wire, 
system  against  the  fall  in  potential  across  a  section 

of  a  standardized  slide  wire  in  which  a  known  current  is  maintained.  An 
elementary  diagram  of  connections  is  shown  in  fig.  1.  The  battery  B  sends 
a  current  through  the  circuit  B-D-C-A-B,  the  value  of  the  current  being 
measured  by  the  ammeter  A.  CD  is  a  uniform  slide  wire  of  known  resistance, 
to  one  end  of  which,  as  at  C,  is  attached  one  end  of  the  thermal-junction  sys- 
tem TT.  The  other  end  of  the  thermal-junction  system  is  connected  through 
the  galvanometer  G  to  a  movable  contact  which  may  be  touched  at  various 
points  along  the  slide  wire  until  a  point  P  is  found  at  which  no  galvanometer 
deflection  results.  The  voltage  of  the  thermal-junction  system  can  then  be 
calculated,  if  desired,  this  being  the  product  of  the  current  expressed  in 
amperes  and  the  resistance  CP  expressed  in  ohms.  The  voltage  of  the  system 
is,  however,  usually  of  secondary  importance;  what  is  desired  is  the  tempera- 


12  TEMPERATURE   FLUCTUATIONS   IN   THE   HUMAN   BODY. 

ture  difference  between  the  two  junctions.  This  might  be  assumed  to  be 
approximately  proportional  to  the  voltage,  but  can  be  obtained  directly  by 
keeping  both  junctions  at  known  temperatures;  in  this  way  the  apparatus 
can  be  calibrated  so  that  different  settings  of  the  contact  correspond  to 
definite  values  of  the  temperature  difference  being  measured.  In  order  to 
make  the  apparatus  direct  reading,  an  additional  resistance  in  series  with 
the  battery  is  almost  universally  used  and  the  current  is  so  adjusted  as  to 
accommodate  itself  to  the  particular  slide-wire  available.  By  bringing  the 
current  to  such  a  value  that  the  fall  in  potential  across  one  division  of  C-D 
is  equal  to  the  voltage  of  the  thermal-junction  system  for  a  temperature 
difference  of  0.01°  C.,  the  apparatus  becomes  practically  direct  reading  in 
hundredths  of  a  degree. 

ADAPTATION  OF  METHOD  FOR  USE. 

The  actual  arrangement,  as  shown  in  fig.  2  (p.  15),  does  not  differ  in  principle 
from  this.  The  storage  battery  B,  which  has  been  partly  discharged  in  order 
to  obtain  a  more  nearly  constant  voltage,  sends  current  continuously  through 
the  circuit  B-R-V1-V2-V3-V4-S  in  parallel  with  P-M-B.  The  resistance  R  is 
fixed,  and  is  placed  in  the  circuit  for  the  purpose  of  bringing  the  current  to  such 
a  value  that  the  apparatus  is  practically  direct  reading;  Vi,  ¥2,  Vs,  and  ¥4  are 
variable  resistances  by  means  of  which  the  current  can  be  maintained  constant 
in  spite  of  slight  changes  in  the  electromotive  force  of  the  storage  cell,  such  as 
might  be  caused  by  a  gradual  discharging  of  the  cell,  temperature  changes,  etc. 
The  shunt  S  is  placed  across  the  potentiometer  P  on  account  of  the  extremely 
low  voltages  to  be  measured.  The  resistance  M  is  so  arranged  that  the  stand- 
ard cell  N  and  galvanometer  G  can  be  closed  across  it,  this  arrangement  forming 
the  equivalent  of  a  very  accurate  ammeter,  so  precise  that  a  high  resistance 
O  is  introduced  into  its  circuit  to  reduce  the  sensitiveness.  Since  the  galva- 
nometer must  be  used  in  connection  with  both  the  standard  cell  and  the 
thermal-junction  circuits,  the  switches  Gi  and  G2  are  provided  for  transferring 
it  from  one  to  the  other.  By  means  of  the  test  switch  T,  the  apparatus  may 
be  tested  for  stray  electromotive  forces.  The  control  switch  K  is  used  for 
convenience  in  bringing  the  galvanometer  to  rest.  The  switches  1,  2,  3,  4,  etc., 
are  also  provided  so  that  the  electromotive  force  of  any  one  of  a  number  of 
thermal-junction  systems  may  be  measured.  To  each  of  these  switches  are 
connected  two  copper  wires,  one  of  which  runs  to  the  body  and  the  other  to  a 
constant-temperature  bath,  these  latter  terminals  being  connected  by  a  con- 
stantan  wire,  which  furnishes  the  second  metal  for  the  thermal  junctions. 

APPARATUS  USED  IN  THE  RESEARCH. 
CONSTANTS   OF   THE   APPARATUS. 

While  considering  the  measurement  from  a  purely  theoretical  standpoint, 
and  before  proceeding  to  a  description  of  the  actual  construction,  it  may  be 
well  to  bring  together  the  constants  of  such  parts  of  the  apparatus  as  were 
available  for  the  work,  and  to  include  the  computations  by  means  of  which 


METHODS  AND  APPARATUS.  13 

the  remaining  constants  were  derived  and  the  suitability  of  the  apparatus 
for  the  work  assured. 

The  potentiometer  has  a  resistance  of  15,000  ohms,  which  can  be  included 
between  the  potential  terminals  in  steps  of  0.1  ohm.  The  galvanometer 
resistance  is  about  50  ohms,  and  the  sensitiveness  such  that  a  deflection  of  0.5 
millimeter  is  produced  by  a  current  of  15  X  10~10  amperes.  The  resistance  of  the 
constantan  wire  as  selected  is  about  14  ohms  for  each  circuit;  that  of  the 
copper  is  negligible.  The  electromotive  force  of  the  copper-constantan  couple 
is  taken  as  40  X  10~6  volts  per  degree  centigrade.  The  voltage  of  the  storage 
cell  is  2.0  volts,  that  of  the  standard  cell  1.0197  volts.  Most  of  the  tempera- 
tures to  be  measured  are  assumed  to  lie  within  the  limits  of  36°  to  38°  C.,  and 
are  desired  to  an  accuracy  of  about  0.01°  C.  The  apparatus,  however,  should 
not  be  restricted  to  these  limits  but  should  be  capable  of  measuring  lower 
temperatures,  although  with  a  somewhat  decreased  precision. 

The  constant-temperature  junction  is  kept  at  a  temperature  of  about  40°  C., 
and  as  the  other  junction  never  rises  to  so  high  a  temperature  as  this,  it  follows 
that  the  net  voltage  of  the  thermal-junction  system  always  acts  in  one  direc- 
tion. The  temperature  difference  between  the  junctions  is  usually  not  less 
than  2°  C.  nor  greater  than  4°  C.,  so  that  under  these  circumstances  the 
voltage  limits  would  be  80  X  10~6  volts  and  160  X  10~6  volts,  between  which 
the  voltage  should  be  determined  to  approximately  0.4  X  10~6  volts. 

The  necessity  for  a  potentiometer  shunt  may  be  very  easily  shown.  If  the 
apparatus  is  to  be  direct  reading — a  change  of  0.4  X  10~6  volts  involving  a 
change  of  0.1  ohm  in  the  potentiometer  setting — then  a  current  of  (0.4  X  10~6) 
-4-  0.1,  or  4  X  10~6  ampere  is  required,  and  this,  if  a  regular  series  circuit  is  used, 
demands  the  use  of  a  circuit  resistance  of  2-r-  (4  X  10~6)  or  500,000  ohms. 
Since  this  is  hardly  practicable,  it  has  been  decided  to  shunt  the  potentiometer, 
leaving  the  current  in  the  potentiometer  itself  4  X  10~6  ampere,  but  taking 
from  the  storage  battery  about  0.01  ampere,  and  causing  the  remainder  to  flow 
through  the  shunt.  For  the  main  current  a  value  of  0.0102  ampere  has  been 
decided  upon,  as  this  permits  the  use  at  M  of  a  100-ohm  coil.  The  value  of  S 
is  then  (4  X  10~6  X  15000)  -=-  (0.0102)  =  5.88  ohms.  The  total  resistance  of  the 
circuit  is  2.0^0.0102  or  196  ohms,  100  ohms  being  taken  by  M  and  about  6 
ohms  by  S  in  parallel  with  P,  leaving  still  90  ohms  necessary  to  be  taken  up  in 
R,  Vi,  V2,  V,,  and  V4. 

To  determine  the  proper  value  for  each  step  of  the  variable  resistances,  it 
must  be  noted  that  while  voltages  as  high  as  160  X  10~6  volts  are  to  be  meas- 
ured, yet  a  deviation  of  0.2  X  10~6  volts  will  in  itself  produce  an  error  in  the 
results  sufficient  to  affect  the  nearest  hundredth  of  a  degree.  From  this  it  is 
seen  that  the  current  must  not  vary  by  2  parts  in  1600,  so  that  each  step  in  the 
variable  resistances  must  not  make  more  than  this  fractional  change  in  the 
resistance,  or  (2  -i-1600)  X  196  =  0.25  ohm.  This  represents  the  maximum 
allowable  change;  consequently  the  steps  in  the  resistance  as  actually  made 
are  smaller  than  this.  The  smallest  steps  are  in  the  resistance  Vs,  which  is 
composed  of  nine  0.1  ohm  coils.  Similarly  V4  comprises  nine  1.0  ohm  coils,  so 


14  TEMPERATURE   FLUCTUATIONS   IN   THE   HUMAN    BODY. 

that  the  combination  gives  a  resistance  of  about  10  ohms,  variable  in  tenths 
of  ohms.  Vi  and  V2  are  provided  should  even  more  adjustment  be  necessary, 
and  have  a  resistance  of  5  ohms  each.  This  gives  20  ohms  for  the  sum  of  the 
variable  resistances,  about  half  of  which  should  be  in  circuit  under  normal 
conditions,  so  as  to  allow  adjustment  in  either  direction.  The  value  for  R 
is  accordingly  90  —  (20-5-2)  =80  ohms. 

To  determine  whether  the  galvanometer  is  sufficiently  sensitive,  it  will  be 
simplest  to  consider  the  case  of  a  measurement  being  made  in  which  the  circuit 
is  not  quite  balanced,  but  owing  to  the  insensitiveness  of  the  galvanometer  it 
appears  to  be  so.  The  largest  current  that  can  pass  through  the  galvanometer 
and  still  be  undetected  is  15  X  10~10  amperes.  This  current  in  flowing  through 
a  resistance  of  64  ohms,  composed  of  the  galvanometer  and  thermal-junction 
system,  causes  a  fall  in  potential  of  15  X  10~10  X  64  or  about  10~7  volts. 
Since  0.01°  C.  corresponds  to  0.4  X  10~6  volts,  or  4  X  10~7  volts,  it  is  seen 
that  the  error  due  to  insensitiveness  of  the  galvanometer  corresponds  to  about 
0.0025°  C.  and  is  therefore  entirely  negligible. 

CONSTRUCTION  OF  THE  APPARATUS. 

Having  determined  the  constants,  or  electrical  dimensions,  of  the  various 
pieces  of  apparatus  considered  in  fig.  2,  the  actual  method  of  construction  and 
installation  will  be  given  in  some  detail.  This  seems  advisable,  since  in  some 
cases  the  peculiar  experimental  conditions  to  be  met  required  a  special  form 
of  construction;  while  in  other  cases  some  of  the  more  elaborate  pieces  of 
apparatus  available,  which  were  not  ideally  adapted  to  the  work,  have  been 
made  to  conform  more  closely  to  the  desired  qualifications. 

MEASURING  INSTRUMENTS. 

Storage  cell. — The  storage  cell  B  is  one  of  a  battery  of  six  cells,  having  a 
normal  rate  of  three-quarters  of  an  ampere  and  provided  with  separate 
terminals  for  each  individual  cell.  A  suitable  resistance,  not  shown  in  fig.  2, 
is  arranged  so  that  it  can  be  connected  across  the  battery  when  desired.  The 
separate  terminals  permit  each  cell  to  be  used  singly,  and  the  resistance  is 
used  partially  to  discharge  the  battery  when  freshly  charged,  thus  causing  its 
voltage  to  be  more  nearly  constant. 

Both  the  storage  cell  and  the  standard  cell  are  provided  with  reversing 
switches,  which  are  mounted  on  a  single  base  and  arranged  so  as  to  be  operated 
together  by  means  of  one  handle.  This  is  done  for  the  following  reason:  The 
electromotive  force  of  the  thermal-junction  system,  standard  cell,  and  storage 
cell  must  all  act  so  as  to  have  a  tendency  to  send  current  through  the  main 
circuit  in  the  same  direction.  For  the  purpose  of  keeping  the  voltage  set  up 
by  the  junction  unidirectional,  the  temperature  of  the  oven  is  always  kept 
higher  than  that  of  the  body.  In  order  to  provide  for  a  possible  decrease  in  the 
oven  temperature,  with  a  consequent  reversal  of  this  voltage,  the  storage  cell 
and  standard  cell  are  furnished  with  the  reversing  switches  just  mentioned. 

The  resistances  R,  Vi,  V2,  V3,  V4,  S,  M,  and  O,  as  well  as  the  coils  in  the 
potentiometer,  are  of  manganin.  Vi  and  V2  are  each  arranged  to  be  short- 


METHODS   AND   APPARATUS. 


15 


circuited  by  knife  switches,  while  V3  and  V4  are  made  up  from  two  dial  switches. 
The  wires  joining  the  main  circuit  to  the  shunted  potentiometer  are  connected 
to  the  terminals  of  the  shunt  rather  than  to  the  terminals  of  the  potentiometer, 
since  the  resistance  of  the  latter  is  very  large  as  compared  with  the  former. 

Potentiometer. — The  potentiometer  used  is  a  combined  potentiometer  and 
Wheatstone  bridge,  made  by  Wolff.1    In  this  type  of  instrument,  the  resist- 


BODY 


OVEN 


FIG.  2.  Complete  wiring  diagram  of  apparatus.    Currentfrom  the  battery  B  flows  through  the  resist- 
ances R,  Vi,  V2,  Vs,  and  V4,  and  then  divides,  part  flowing  through  the  shunt  S  and  part 
tiometer  P,  the  total  current  finally  returning  to  B  through  the  resist- 


through  the  potent 
anceM.    The  potei 


The  potentiometer,  which  is  composed  of  5  variable  resistances  is  joined  to  the 
switching  arrangement,  of  which  Gi  connects  the  galvanometer  G  in  circuit,  T  replaces 
the  thermal-junction  system  when  testing,  and  1,  2, 3, 4,  etc.,  are  connected  to  the  thermal- 
junctions  at  the  body  and  the  constant-temperature  oven.  The  constantan  wires  are 
indicated  by  the  heavy  lines.  N  is  the  standard  cell,  protected  by  the  high  resistance 
O,  and  connected  to  the  circuit  through  the  double-contact  key  Gi.  The  switch  K  is  for 
convenience  in  bringing  the  galvanometer  to  rest. 


'Wolff,  Zeitsch.  f.  Instrumentenkunde,  1903,  Oktober. 


16  TEMPERATURE   FLUCTUATIONS   IN    THE   HUMAN    BODY. 

ance  is  kept  constant  regardless  of  the  position  of  the  contacts  by  the  device 
of  two  identical  circuits,  one  of  which  is  included  between  the  sliding  contacts 
while  the  other  is  not;  these  circuits  being  so  arranged  mechanically  that  as 
the  resistance  of  one  is  decreased  the  resistance  of  the  other  is  increased  by 
the  same  amount.  This  arrangement  has  the  disadvantage  that  contact 
resistance  in  the  potentiometer  circuit  may  affect  not  only  the  precision  but 
also  the  accuracy  of  the  measurement.  In  choosing  apparatus  for  similar 
work,  it  should  be  noted  that  this  is  an  unnecessary  handicap,  since  the  poten- 
tiometer may  be  so  designed  as  not  to  require  any  contact  in  this  very  import- 
ant part  of  the  circuit.  Also  for  thermo-electrical  work,  the  potentiometer 
should  have  low  resistance,  so  as  to  retain  the  full  sensitiveness  of  the 
apparatus. 

The  potentiometer  shunt  is  embedded  in  a  block  of  paraffin,  together  with 
the  brass  binding  posts  of  the  potentiometer;  also  a  similar  block  is  used  where 
the  copper  wires  join  the  binding  posts  which  are  connected  to  the  moving 
contacts.  None  of  the  knife  switches  G2,  T,  1,  2,  3,  4,  etc.,  contain  any 
junction  of  dissimilar  metals,  the  circuit  being  copper  throughout.  Moreover, 
these  switches  are  mounted  at  a  distance  of  about  1  meter  from  the  observer 
and  are  operated  by  means  of  long  wooden  rods.  This  construction  is  adopted 
in  view  of  the  fact  that  in  some  parts  of  the  circuit,  namely,  in  the  poten- 
tiometer, the  shunt,  the  switches  just  mentioned,  the  galvanometer,  and  the 
thermal-junction  systems,  it  is  very  important  to  reduce  as  much  as  possible 
all  stray  electromotive  forces. 

The  unavoidable  junctions  occur  mostly  in  the  form  of  reversed  pairs;  the 
paraffin  blocks,  by  surrounding  both  these  junctions  with  a  medium  having  an 
appreciable  mass,  lessen  the  effect  of  transient  fluctuations  in  the  room  temper- 
ature; furthermore,  as  these  blocks  have  a  greater  heat-carrying  capacity  than 
air,  they  provide  a  better  path  for  the  transfer  of  heat  between  the  two  junc- 
tions, thus  tending  to  equalize  the  temperature  of  the  two.  The  slender 
wooden  rods  are  used  in  connection  with  the  switches  as  a  further  safeguard 
at  these  points  to  prevent  heating  from  the  hand. 

Standard  cell. — The  resistance  M  is  furnished  in  the  usual  way  with  both 
current-  and  potential-terminals.  The  standard  cell  N  is  a  Weston  Standard 
Cell,  No.  1565,  provided  with  the  usual  certificate  stating  its  electromotive 
force.  The  following  caution  is  expressed  in  the  certificate:  "To  preserve 
the  constancy  of  this  cell,  it  should  not  be  exposed  to  temperatures  below  4°  C., 
and  no  current  greater  than  0.0001  ampere  should  be  passed  through  it." 
The  insertion  of  the  resistance  0  of  10,000  ohms  assures  the  fulfilment  of  this 
latter  requirement,  and  at  the  same  time  leaves  an  arrangement  amply  sensi- 
tive. The  switch  Gi  is  in  the  form  of  a  double-contact  key,  which  remains 
open  unless  pressed,  thus  preventing  the  standard  cell  circuit  from  remaining 
closed  accidentally. 

^  Galvanometer.— The  galvanometer  is  a  reflecting  instrument  of  the  Deprez- 
d'Arsonval  type,  manufactured  by  Siemens  &  Halske.  Among  the  advantages 
of  this  instrument  might  be  mentioned  first,  that  provision  is  made  whereby 


METHODS   AND   APPARATUS.  17 

the  whole  moving  system  may  easily  be  taken  out  and  replaced  by  another, 
perhaps  of  different  resistance  or  sensitiveness;  second,  that  small  windows 
are  provided  at  the  top  and  bottom  of  the  suspension  strip,  by  means  of  which 
it  may  easily  be  inspected  or  removed.  The  chief  disadvantage  for  general 
work  is,  perhaps,  that  when  the  instrument  is  set  up  the  moving  coil  is  not 
visible  and,  the  clearance  being  small,  leveling  becomes  comparatively  difficult. 
The  resistance,  50  ohms,  is  rather  too  high  for  work  of  this  character;  prob- 
ably a  smaller  resistance  could  have  been  used  and  still  leave  an  instrument 
of  sufficient  sensitiveness.  The  galvanometer  is  not  entirely  free  from  thermal 
electromotive  forces;  indeed,  this  could  hardly  be  the  case  where  a  number 
of  metals  are  in  circuit.  This  disturbing  effect  has  been  found  to  be  less, 
however,  in  an  instrument  purchased  in  1907  than  in  a  later  model  purchased 
in  1909.  With  a  view  toward  reducing  extraneous  electromotive  forces  in 
the  galvanometer,  it  has  been  shielded  as  much  as  possible  from  temperature 
changes  by  placing  over  it  a  cork-lined  wooden  box.  This  is  provided  with 
a  door  at  the  side  for  inspection,  leveling,  etc.,  and  with  a  transparent  celluloid 
window  in  front  through  which  the  rays  of  light  can  pass.  Since  the  use  of 
a  telescope  for  reading  was  regarded  as  too  tiring  for  repeated  observations, 
a  ground-glass  scale  at  a  distance  of  almost  4  meters  has  been  used,  upon 
which  the  reflection  of  the  filament  of  an  incandescent  lamp  is  focussed.  If 
too  long  a  scale  distance  should  be  used,  in  the  attempt  to  increase  the  sensi- 
tiveness, a  blurred  image  will  result,  caused  by  slight  imperfections  in  the 
surface  of  the  mirror. 

The  galvanometer  has  been  mounted  in  the  following  way:  A  location 
was  chosen  near  a  structural  steel  upright  on  the  street  floor  of  the  building 
and  a  strong  shelf  built  out  from  the  wall  at  this  point.  Upon  the  shelf  was 
placed  a  square  block  of  cork,  3  or  4  cm.  thick,  to  which  was  fastened  a  1.25 
centimeter  iron  plate,  and  on  this  the  galvanometer  was  mounted.  The  very 
slight  vibration  of  the  shelf  resulting  from  the  jar  of  the  building  is  damped 
out  by  the  cork,  which  acts  as  a  spring. 

The  copper  wires  running  to  the  thermal  junctions  have  a  diameter  of 
1.63  millimeters  up  to  within  1  or  2  meters  from  the  junction  itself.  At  this 
point  they  are  joined  to  smaller  copper  wires  (0.455  millimeter),  thus  making 
the  junctions  smaller  and  more  flexible.  The  wiring  should  be  done  in  such  a 
way  as  to  leave  no  avoidable  loops  in  the  circuit;  this  will  eliminate  the  induc- 
tive action  of  neighboring  circuits,  which  otherwise  might  cause  annoying 
deflections  of  the  galvanometer. 

THERMAL-JUNCTION  SYSTEM. 

Thermometers  for  internal  temperatures. — Most  of  the  junctions  used  for 
measuring  temperature  in  the  natural  and  artificial  cavities  of  the  body  are 
simply  twisted  and  soldered  joints  between  two  wires — one  of  constantan 
(0.455  millimeter)  and  the  other  of  copper  (0.455  millimeter).  For  taking 
internal  temperatures  a  construction  like  A  (fig.  3)  is  employed,  in  which  the 
two  wires  run  side  by  side,  one  of  them  being  inclosed  in  a  rubber  tube  for 


18  TEMPERATURE    FLUCTUATIONS   IN   THE   HUMAN    BODY. 

insulation.  The  wires  are  then  twisted  and  soldered  together  in  the  usual 
way,  tied  with  silk,  and  finally  covered  with  thin  pure  gum  tubing.  Before 
insulating  the  bare  copper  wire,  however,  the  precaution  is  taken  to  protect 
it  from  the  corrosive  action  of  the  sulphur  in  the  rubber  by  "tinning"  it 
or  covering  it  with  solder.  It  was  found  that  the  lag  of  the  thermometer, 
due  to  the  rubber  tubing,  was  about  2.5  minutes;1  this  was  regarded  as  being 
not  too  great. 

For  taking  temperatures  in  the  axilla  a  thermometer  of  the  type  illustrated 
under  B,  fig.  3,  recommends  itself.  Here  the  joint  is  made  by  twisting  and 
soldering  two  wires  which  approach  each  other  from  opposite  directions,  the 
inclosure  in  tubing  being  the  same  as  before. 

Another  type  of  thermometer  is  shown  in  C,  fig.  3.  Here  one  of  the  metals 
of  the  junction  touches  the  body  without  the  intervention  of  any  isolating 
material,  so  that  the  conditions  for  the  taking  up  of  the  temperature  by  the 
thermometer  are  ideal.  The  copper  element  is  made  in  the  form  of  a  very 


Fio.  3.  Types  o{  thermal-junction  thermometers  used.  A,  junction  inclosed  in  rubber  tube,  used 
principally  for  internal  measurements;  B,  same,  arranged  for  use  in  axilla;  C,  junction  in 
which  one  metal  touches  body,  for  taking  internal  temperatures;  D,  modification  of  this 
type  for  surface  measurements. 

thin  hollow  thimble,  to  the  inside  of  which,  at  the  end,  is  soldered  the  con- 
stantan  wire,  properly  insulated.  A  copper  wire  soldered  to  the  thimble 
completes  the  circuit.  The  connecting  wires  and  the  open  end  of  the  cap  are 
covered  by  rubber  tubing,  and  tied  with  silk,  after  which  the  copper  is  silver- 
plated.  This  arrangement  fulfils  the  theoretical  condition  that  both  elements 
should  not  touch  the  skin,  and  at  the  same  time  provides  an  excellent  thermal 
relation  between  the  thermometer  and  the  body  whose  temperature  is  being 
measured. 

Thermometers  for  surface  temperature. — The  attempts  made  to  obtain  accu- 
rate measurements  of  the  surface  temperature  were  not  successful,  but  a  brief 
description  of  the  thermometers  used  may  be  of  interest.  Several  types  of 
skin  thermometers  were  constructed.  At  first  the  ordinary  rubber-covered 

'The  method  of  testing  the  thermal-junction  thermometers  for  lag  was  as  follows:  The 
thermometer  being  tested  was  connected  to  the  measuring  circuit  and  suddenly  thrust 
into  a  flask  of  water  at  about  body  temperature.  This  caused  a  galvanometer  deflection 
wnicn  at  hrst  changed  rapidly  but  gradually  became  more  nearly  constant  and  finally 
could  not  be  observed  to  change  at  all,  the  change  in  deflection  corresponding  to  the 
change  in  temperature  of  the  junction.  The  length  of  time  noted  above  (2.5  minutes) 
is  tne  interval  elapsing  from  the  instant  when  the  thermometer  was  immersed  until  the 
deflection  had  become  constant. 


METHODS   AND   APPARATUS. 


19 


thermometers,  A  or  B,  fig.  3,  were  used,  these  being  held  in  place  by  a  bandage; 
afterwards  they  were  pressed  somewhat  into  the  flesh  by  placing  them  under 
small  pieces  of  wood  which  were  strapped  in  position.  A  later  type  is  shown 
in  D,  fig.  3.  Here  the  general  shape  of  the  thermometer  is  along  the  lines 
finally  used  by  Gamgee.1  The  support  consists  of  a  cork  disk,  somewhat 
rounded  on  the  face.  To  this  is  shellacked  a  piece  of  thin  sheet  copper,  shaped 


so  as  to  bulge  outward  from  the  support.  This  copper  plate  furnishes  one  of 
the  metals  of  the  thermo-couple,  a  constantan  wire  soldered  to  the  center  of 
the  back  supplying  the  other,  and  a  copper  wire,  also  soldered  to  the  plate, 
completing  the  circuit.  The  base  is  made  of  cork  in  order  to  give  the  apparatus 
a  smaller  mass,  and  the  copper  is  shaped  in  the  manner  described  so  that  it  may 

:Gamgee,  loc.  cit. 


20  TEMPERATURE   FLUCTUATIONS   IN   THE   HUMAN   BODY. 

press  into  the  flesh  and  take  up  the  deeper  temperature.  The  thermometer  is 
held  in  place  by  a  cloth  strap.  The  junction  itself  must  be  shielded  so  that  it 
may  take  up  the  body-temperature,  and  yet  this  must  not  interfere  with  the 
natural  liberation  of  heat.  These  two  conditions  are  incompatible,  but  the 
shape  of  thermometer  chosen  seems  to  fulfil  both  as  well  as  possible. 

Thermal  junctions  used  in  the  constant-temperature  bath. — The  thermal 
junctions  used  in  the  constant-temperature  bath  are  all  made  in  the  same  way. 
The  two  small  wires  are  slipped  into  separate  capillary  rubber  tubes  and  a 
soldered  joint  made  exactly  as  in  type  A  (fig.  3)  previously  described.  The 
different  junctions  are  then  supported  in  the  following  manner:  A  piece  of 
glass  tubing  (A,  fig.  4)  is  used,  about  15  centimeters  long  and  having  a  16 
millimeter  bore.  The  upper  end  of  this  tube  is  passed  through  a  block  of 
wood  B  and  secured  with  silk  and  shellac.  Along  the  outside  walls  of  the 
tube  the  thermal-junction  wires  C  are  laid,  and  firmly  tied  with  silk  in  such  a 
way  as  to  leave  the  junctions  protruding  1  or  2  centimeters  from  the  bottom 
of  the  tube.  The  ends  of  the  junctions  are  carefully  separated,  and  the 
whole  arrangement  dipped  in  paraffin.  The  paraffined  junctions,  together 
with  the  glass  tube,  are  then  immersed  in  water  contained  in  a  large  spherical 
Dewar  vacuum  flask  D  with  silvered-glass,  double  walls.  This  flask  has  an 
outside  diameter  of  about  15  centimeters,  the  distance  between  the  walls  being 
8  millimeters,  the  length  of  the  neck  approximately  10  centimeters,  and  the 
capacity  1100  cubic  centimeters. 

A  mercury  thermometer,  E,  which  indicates  the  temperature  of  the  bath, 
passes  through  the  tube  A  to  such  a  depth  that  its  bulb  lies  very  near  the 
thermal  junctions  and  at  the  same  level.  This  construction  allows  the  ther- 
mometer to  take  up  the  temperature  of  the  junctions  very  closely.  The 
mercury  thermometer  is  of  the  Beckmann  type,  having  a  range  of  5°  C.,  is 
graduated  in  hundredths  of  a  degree,  and  calibrated  by  the  Physikalisch- 
Technische  Reichsanstalt.  The  true  temperature,  as  obtained  from  the  read- 
ing of  such  a  thermometer,  would  be  expressed  by  the  formula  T=A+KR, 
where  T  is  the  temperature  desired,  A  being  the  zero  reading  of  the  thermome- 
ter, K  a  calibration  constant  which  equals  the  true  value  of  a  scale  division 
for  the  particular  conditions  of  use,  and  R  the  reading. 


CONSTANT-TEMPERATURE   OVEN. 


The  flask  D  is  placed  in  an  oven,  F  (see  fig.  5),  in  which  the  air  is  maintained 
at  a  constant  temperature  by  the  use  of  a  mercury  thermostat  G  which  auto- 
matically supplies  the  proper  amount  of  gas  to  a  small  burner  H  located 
beneath  the  oven.  This  oven,  which  is  of  sheet  metal  and  about  33X40X50 
centimeters,  is  inclosed  in  a  slightly  larger  asbestos  case  with  a  sheet-metal 
bottom,  the  air  space  between  the  oven  and  the  outside  case  being  about  25 
millimeters.  The  fronts  of  both  are  hinged;  in  the  top  are  three  holes,  one  for 
the  insertion  of  the  thermostat,  one  for  the  mercury  thermometer  E,  and  one 
for  the  insertion  of  the  wires  of  the  thermal-junction  system.  Through  the 
last  opening  is  also  inserted  a  mercury  thermometer  for  indicating  roughly  the 


METHODS   AND   APPARATUS. 


21 


temperature  of  the  air  in  the  oven,  and  a  tube  for  compressed  air.  By  means 
of  this  tube  compressed  air,  which  has  previously  been  passed  through  an 
indicator  outside  of  the  oven,  is  conducted  into  a  bottle  of  water  placed  in  the 
oven,  and  finally  passes  in  a  succession  of  bubbles  up  through  the  water  in  the 
Dewar  flask  itself. 

By  automatically  keeping  the  air  in  the  oven  at  the  same  temperature  as  the 
water  in  the  flask,  any  small  heat  loss  from  the  flask  is  avoided.  The  outer 
air-space  and  asbestos  casing  also  aid  in  the  temperature  control  of  the  oven, 
while  the  metal  bottom  assists  in  the  equalization  of  the  heat  from  the  burner. 

It  was  at  first  thought  that,  with  the  flask  surrounded  by  ideal  conditions, 


FIG.  5.  Constant-temperature  oven.  Inside  the  oven  F,  in  the  center,  is  shown  the  constant-tempera- 
ture flask  D,  with  the  mercury  thermometer  E.  On  the  right  is  the  thermostat  G  which 
supples  gas  to  the  burner  H  below  the  oven;  at  the  left  is  the  arrangement  1 1  supplying  com- 
pressed air  for  stirring  the  water  in  the  flask  D. 

sufficient  stratification  could  hardly  exist  to  produce  a  sensible  error  in  the 
reading.  It  was  found,  however,  that  appreciable  temperature  differences  did 
exist  in  the  flask  and,  although  the  thermometer  bulb  and  thermal  junctions 
were  all  at  the  same  level,  it  was  considered  advisable  to  provide  some  method 
of  stirring.  For  this  reason,  compressed  air  was  introduced,  being  selected  as 
a  convenient  method  for  stirring  the  bath,  especially  in  view  of  the  fact  that 
the  space  available  was  small.  By  passing  the  air  first  through  a  vessel  of 
water  inside  the  oven  it  is  brought  to  the  temperature  of  the  water  in  the  flask 
and,  still  more  important,  is  saturated  with  moisture  at  the  same  tempera- 
ture, so  that  no  heat  is  lost  either  by  absorption  or  by  evaporation. 


22 


TEMPERATURE   FLUCTUATIONS   IN   THE   HUMAN    BODY. 


To  prevent  cooling  by  evaporation  from  the  surface,  the  water  in  the  flask 
was  at  first  covered  by  a  thin  film  of  oil;  but  this  necessitated  such  an  elabo- 
rate arrangement  to  protect  the  rubber  tubing  that  the  oil  is  now  omitted, 
with  equally  satisfactory  results.  The  performance  of  the  constant-tempora- 
ture  oven  has  proved  very  satisfactory,  the  temperature  within  the  flask 
frequently  not  changing  more  than  0.01°  C.  in  an  hour. 

CALIBRATION  OF  MERCURY  THERMOMETERS. 

The  following  is  an  abstract  of  the  calibrations  of  the  various  thermometers 
used  in  the  work,  as  given  by  the  Physikalisch-Technische  Reichsanstalt. 
In  the  case  of  the  Beckmann  thermometers,  data  are  given  showing  how  the 
constant  K,  previously  mentioned,1  is  determined.  The  tables  of  corrections 
for  variations  in  caliber  have  been  omitted  in  the  Beckmann  calibrations,  but 
a  statement  is  made  regarding  the  maximum  value  of  the  correction. 
Beckmann  Thermometer  PTR  40724. 


Range. 

Average  tem- 
perature of 
exposed  stem. 

Value  of  scale 
division  Jena 
glass  16»». 

Correction. 

Corrected 
value  of  scale 
division. 

30-35 
40-45 

22 
24 

1.013 
1.017 

-0.008 
-0.008 

1.005 
1.009 

Since  the  thermometer  is  to  be  used  at  temperatures  of  37°  to  42°  C.,  an 
interpolation  has  been  made  in  the  above  table,  giving  as  the  corrected  value 
of  a  scale  division, 

1.005+[(37-30)H- (40-30)]  (1.009 -1.005)  =  1.008 
No  caliber  correction  greater  than  0.005°  C.  is  given,  so  that  for  readings 
only  to  0.01°  C.,  this  correction  is  negligible. 

Beckmann  Thermometer  PTR  40723. 


Range. 

Average  tem- 
perature of 
exposed  stem. 

Value  of  scale 
division  Jena 
glass  16'". 

Correction. 

Corrected 
value  of  scale 
division. 

30-35 

22 

1.013 

-0.006 

1.007 

40-45 

24 

1.017 

-0.006 

1.011 

This  thermometer  is  to  be  used  in  calibrating  at  temperatures  of  34°  to  39°  C. 
The  corrected  value  of  a  scale  division  is  therefore: 

1.007  +[(34 -30) -4- (40 -30)]  (1.011 -1.007)  =  1.009 
No  caliber  correction  greater  than  0.005°  C.  is  given. 
Richter  Thermometer  PTR  32689. 

Range  34°-44°  C.,  graduated  in  0.01°  C.     Without  sensible  error  throughout, 
i.  e.,  no  correction  so  great  as  0.005°  C. 

In  calibrating  a  Beckmann  thermometer  in  this  laboratory,  its  zero  point 
was  determined  roughly,  and  then  the  thermometer  was  set  by  trial  until  the 

'Page  20. 


METHODS   AND   APPARATUS. 


23 


desired  value  was  approximately  obtained.  A  careful  determination  was  then 
made  by  tying  the  Beckmann  and  Richter  thermometers  together  and  immers- 
ing the  pair  in  a  Dewar  flask  similar  to  that  used  in  the  constant-temperature 
oven.  The  flask  was  filled  with  warm  water  stirred  by  compressed  air,  and 
immersed  in  a  large  body  of  hot  water  in  an  outside  pail,  the  temperature  of 
this  outside  water  being  regulated  by  an  electric-coil  heater.  This  heater  is 
simply  a  resistance  wire  inclosed  in  a  water-tight  spiral  tube,  having  in  its 
outside  electrical  circuit  a  variable  resistance,  so  that  the  amount  of  heating 
can  be  controlled.  Several  simultaneous  readings  of  the  thermometers  were 
taken,  as  shown  by  the  data  given  in  table  1  which  represent  the  determina- 
tion of  the  zero  point  of  Beckmann  thermometer  40724,  used  in  the  constant- 
temperature  oven.  The  Beckmann  reading,  corrected  for  caliber  errors,  must 
be  multiplied  by  1.008 — the  constant  determined  from  the  above  calibra- 
tion— and  subtracted  from  the  true  temperature  in  order  to  give  the  zero 
point  of  the  thermometer. 

TABLE  1. — Determination  of  zero  point,  Beckmann  thermometer  PTR  40724. 


Beckmann  thermom- 

Richter 
thermometer 
32689  reading. 

eter  40724. 

Corrected 
reading 
multiplied 
by  1.008. 

Zero  point  of 
Beckmann 
thermometer. 

Deviation 
from  av. 

Reading. 

Corrected 
reading. 

39.04 

.735 

1.731 

1.75 

37.29 

0.010 

39.04 

.735        1.731          1.74               37.30          .000 

39.04      i       .732 

1.728    !      1.74               37.30    i       .000 

39.04            .728 

1.724    i      1.74    '"            37.30    !       .000 

39.04 

.726 

1.722          1.74                37.30    i       .000 

39.04 

.725 

1.721          1.73 

37.31     i       .010 

39.02 

.712 

1.708 

1.72 

37.30 

.000 

39.01             .702 

1.698 

1.71 

37.30 

.000 

A  v.-  37.  800 

0.003 

Thus  the  correct  temperature  as  determined  from  a  reading  of  this  ther- 
mometer is  given  by  the  formula  37.300+1. 008  X  reading.    When  working  only 
to  hundredths,  the  formula  37.30+1. 01 X  reading  gives  closer  results  at  the 
lower  part  of  the  scale,  but  37.29+1.01  Xreading  is  better  on  higher  readings. 
METHOD  OF  OPERATING  APPARATUS. 

In  measuring  temperatures  with  this  apparatus  the  procedure  is  first  to 
connect  the  partly  discharged  cell  to  the  measuring  circuit  for  a  few  minutes 
in  order  to  let  the  current  become  constant,  and  then  carefully  to  depress  the 
key  Gi.  In  general,  a  galvanometer  deflection  results,  indicating  that  the 
current  differs  from  its  standard  value.  By  regulating  the  variables  V3  and 
V4,  and  also,  if  necessary,  Vi  and  V2,  this  deflection  is  brought  as  nearly  as 
possible  to  zero,  thus  indicating  that  the  current  has  closely  enough  its  proper 
value.  The  current  having  been  adjusted,  the  next  step  is  to  close  G2  and 
one  of  the  switches  1,  2,  3,  4,  etc.,  according  to  which  thermal  junction  is  to  be 
used.  In  general  a  deflection  results,  which  can  be  almost  balanced  by 
properly  moving  the  potentiometer  contacts.  The  attempt  is  not  made  to 


24  TEMPERATURE   FLUCTUATIONS   IN   THE   HUMAN   BODY. 

balance  exactly,  as  this  requires  some  time,  but  after  the  balance  has  been 
obtained  within  perhaps  0.1°  C.,  the  potentiometer  setting  and  the  deflection 
are  observed  and  noted.  From  time  to  time  the  current  is  checked  as  at  the 
beginning,  also  the  temperature  of  the  constant-temperature  bath  is  occasion- 
ally taken  and  the  correction  for  extraneous  electromotive  force  determined. 
For  the  purpose  of  making  this  last  test  the  test  switch  T  is  provided.  The 
connections  are  such  that  if  this  switch  is  closed,  instead  of  one  of  the  switches 
1,  2,  3,  4,  etc.,  the  apparatus  is  in  the  condition  usual  for  a  temperature 
measurement,  except  that  the  thermal-junction  system  is  replaced  by  a  direct 
copper  connection.  The  electromotive  force  in  this  circuit  should  then  be  zero, 
and  if  the  potentiometer  is  set  at  zero,  a  balance  should  be  obtained.  If  this 
is  not  the  case,  a  galvanometer  deflection  will  result,  indicating  the  presence 
of  an  extraneous  electromotive  force.  This  error  may  be  determined  either 
by  changing  the  potentiometer  setting  until  a  balance  is  obtained,  or  else — 
having  a  knowledge  of  the  sensitiveness  of  the  galvanometer — by  interpreting 
it  directly  from  the  deflection.  The  latter  method,  being  quicker,  is  perhaps 
preferable;  it  also  frequently  saves  reversing  the  storage  cell  and  standard 
cell,  which  would  be  necessary  in  balancing  if  the  stray  electromotive  force 
happens  to  oppose  the  main  voltage  of  the  thermal-junction  system. 

CALIBRATION    OF    THERMAL  JUNCTIONS. 

In  calibrating  the  thermal  junctions,  a  Dewar  flask  was  used,  similar  to  that 
in  the  constant-temperature  oven.  This  was  filled  with  water  at  about 
body-temperature  and  immersed  in  a  considerable  mass  of  warm  water  in  a 
pail,  the  temperature  of  the  outside  water  being  controlled  by  an  electric-coil 
heater.  The  Beckmann  thermometer  (40723),  already  described,  and  all 
the  junctions  to  be  calibrated  were  placed  side  by  side  and  bound  together 
with  rubber  bands  in  such  a  way  as  to  bring  the  junctions  at  about  the  middle 
of  the  bulb,  but  without  pressure  on  the  bulb  itself.  The  thermometer  and 
junctions  were  then  inserted  in  the  calibrating  flask,  the  surrounding  water 
being  stirred  by  compressed  air  from  the  supply  in  the  constant-temperature 
oven.  After  the  temperature  in  the  calibrating  flask  had  become  constant  the 
Beckmann  thermometer  was  read,  the  necessary  potentiometer  readings  were 
made  for  each  thermal  junction,  and  the  reading  of  the  Beckmann  thermometer 
in  the  constant-temperature  oven  was  taken.  Usually  four  complete  series 
of  readings  were  made  as  quickly  as  possible;  their  average  furnished  data 
which  showed  the  relation  between  temperature  difference  and  potentiometer 
balance  for  this  point.  After  this  another  temperature  was  used  in  the  cali- 
brating flask  and  similar  data  obtained.  In  this  way  the  junctions  were 
calibrated  throughout  the  range  of  temperature  difference  likely  to  occur  in 
an  actual  experiment.1 


'These  conditions  are  also  suitable  fortesting  the  constantan  wireforinhomogeneity.  The 
most  important  part  of  the  circuit,  namely,  that  where  the  temperature  gradient  is  usually 
steepest  and  most  variable,  occurs  near  the  junction  for  use  on  the  body.  This  region  may  be 
explored  by  keeping  the  junction  at  a  fixed  temperature  in  the  bath,  meantime  immersing 
the  wires  to  varying  depths.  A  number  of  tests  made  in  this  way  showed  no  change  in  the 
galvanometer  deflection,  indicating  that  the  wire  was  sufficiently  homogeneous  for  this  work. 


METHODS  AND  APPARATUS. 


25 


Part  of  an  actual  calibration  will  serve  to  show  the  nature  of  the  results 
obtained.  After  the  preliminary  adjustment  of  the  current  the  following 
data  were  taken:  First,  the  temperature  in  the  flask,  then  as  quickly  as 
possible  the  potentiometer  readings  for  the  junctions  A,  B,  C,  D,  E,  F,  and  G. 
It  might  be  remarked  that  the  potentiometer  setting  was  kept  fixed  throughout 
and  the  deflections  noted;  this  saved  a  great  deal  of  time.  These  were 
quickly  followed  by  a  second  reading  of  the  temperature  in  the  flask,  and  also 
a  reading  of  the  temperature  in  the  constant  oven.  Finally  the  stray  electro- 
motive force  was  measured  and  the  current  balanced  as  before.  Then  the 
series  of  observations  was  immediately  repeated.  The  mercury  thermometers 
were  read  to  0.002°  C.,  and  the  deflections  to  the  nearest  half  millimeter. 
The  data  are  given  in  table  2. 

TABLE  2.— Calibration  of  thermal  junctions,   February  1,   1911. 


Initial  temper- 
ature in  flask  .  . 

Potentiometer 
readings  : 
Junction  A.  .  . 
Junction  B  .  .  . 
Junction  C.  .  . 
Junction  D  .  .  . 
Junction  E.  .  . 
Junction  F.  .  . 
Junction  G.  .  . 

Final  tempera- 
ture in  flask  . 
Temperature 
in  oven  
Stray    deflec- 
tion   
Current     bal- 
ance* 

3.774 

3.770 

3.775 

3.745 

Averages 
3.76?" 

Setting. 

Defl. 

Setting. 

Defl. 

Setting. 

Defl. 

Setting. 

Defl. 

Setting 

Defl. 

ohms 
18.00 
18.00 
18.00 
18.00 
18.00 
18.00 
18.00 

mm. 
±0.0 
+5.0 

+7.5 
+5.0 
+2.5 
+7.0 
+7.0 

ohms 
18.00 
18.00 
18.00 
18.00 
18.00 
18.00 
18.00 

mm. 
-1.5 
+4.0 
+6.0 
+4.0 
+  1.0 
+6.0 
+6.0 

ohms 
18.00 
18.00 
18.00 
18.00 
18.00 
18.00 
18.00 

Wl  Wl. 

-4.0 
+1.5 
+3.5 
+2.0 
-0.5 
+4.0 
+4.0 

ohms 
18.00 
18.00 
18.00 
18.00 
18.00 
18.00 
18.00 

mm. 
-5.5 
±0.0 

+2.5 
±0.0 
-2.5 

+2.5 
+2.0 

ohms 
18.00 
18.00 
18.00 
18.00 
18.00 
18.00 
18.00 

mm. 
-2.7 
+2.6 
+4.9 
+2.7 
+0.1 
+4.9 
+4.8 

3.774 

2.458 
+3.  Omm. 
6.8  ohms 

3.770 
2.458 

+2.5  mm. 
6.7  ohms 

3.775 
2.459 
+3.  Omm. 
6.6  ohms 

3.740 
2.459 
+4.  Omm. 
6.  6  ohms 

3.760 
2.459 
+3.1  mm. 

JNot  used  in  computations.    The  figure  given  is  the  reading  of  the  variable  resistance  when  the  current  is  balanced. 
COMPUTATIONS    FOR   THE    CALIBRATION. 

The  corrected  potentiometer  balance  differs  from  the  setting  in  two  respects: 
(1)  correction  for  stray  electromotive  force  must  be  made,  and  (2)  since  the 
balance  consists  partly  of  a  setting  and  partly  of  a  deflection,  the  effect  of 
this  deflection  must  be  included. 

The  correction  for  stray  electromotive  force  is  obtained  in  direction  and 
amount  by  consideration  of  the  following  facts:  The  galvanometer  connec- 
tions are  such  that  a  positive  deflection  requires  a  decrease  in  the  potentiom- 
eter setting  to  bring  it  to  0;  therefore,  a  positive  stray  deflection,  such  as  is 
seen  in  table  2,  by  demanding  a  further  decrease  in  the  potentiometer  setting, 
which  is  already  0,  indicates  a  stray  electromotive  force  opposite  in  direction 
to  the  net  electromotive  force  of  the  thermal-junction  system.  Hence,  the 


26  TEMPERATURE   FLUCTUATIONS   IN   THE   HUMAN   BODY. 

potentiometer  setting  would  have  been  greater  had  it  not  been  for  the  presence 
of  this  extraneous  electromotive  force,  and  so  the  correction  must  be  added. 
The  actual  magnitude  of  the  stray  correction  is  determined  from  the  galvan- 
ometer sensitiveness  and  the  average  stray  deflection.  The  sensitiveness 
of  the  galvanometer  has  been  found  by  trial  to  be  such  that  when  taking  the 
stray  correction — which  necessitates  setting  the  potentiometer  at  0 — a 
deflection  of  25  millimeters  corresponds  to  a  change  in  the  potentiometer 
setting  of  1  ohm,  so  that  a  deflection  of  1  millimeter  corresponds  to  a  change 
in  setting  of  1  -f-  25  or  0.040  ohm.  The  average  stray  deflection  in  the  calibra- 
tion just  given  is  3.1  millimeters.  This,  it  is  seen,  is  equivalent  to  a  change  in 
setting  of  0.040X3.1  or  0.12  ohm,  which  is  therefore  the  correction  that  must 
be  added  to  the  setting  on  account  of  the  stray  electromotive  force. 

When  taking  the  readings  of  the  thermal  junctions,  the  potentiometer 
setting  is  no  longer  0,  but  is  increased  in  the  present  instance  to  18  ohms. 
This  change  increases  the  resistance  of  the  galvanometer  circuit  and  thus 
reduces  its  sensitiveness,  so  that  under  the  new  conditions  a  deflection  of 
1  millimeter  has  been  found  by  trial  to  correspond  to  a  change  in  setting  of 
0.063  ohm.  As  before,  a  positive  deflection  is  equivalent  to  a  decreased 
balance.  Thus,  the  final  corrected  balances  for  the  different  junctions  are: 

A,  18.00+0.12+2.7X0.063  =  18.29 

B,  18.00+0.12-2.6X0.063  =  17.96 

C,  18.00+0.12-4.9X0.063  =  17.81 

D,  18. 00+0'.  12-2. 7X0. 063  =  17. 95 

E,  18.00+0.12-0.1X0.063  =  18.11 

F,  18.00+0.12-4.9X0.063  =  17.81 

G,  18.00+0.12-4.8X0.063  =  17.82 

The  temperature  difference  is  determined  from  the  average  readings  of  the 
two  Beckmann  thermometers,  one  in  the  constant-temperature  oven,  the  other 
in  the  calibrating  flask.  The  temperature  in  the  constant-temperature  oven 
is  given  by  the  formula  previously  deduced  :T 

Temperature  in  oven  =  37 . 300  + 1 . 008  X  reading 

=  37. 300+1. 008X2. 459=39. 779°  C. 

Similarly  the  temperature  in  the  calibrating  flask  is  given  by  the  formula: 
Temperature  in  flask  =  34 . 365 + 1 . 009  X  reading 

=  34. 365  +  1. 009X3. 761=38. 160°  C. 

The  temperature  difference  is  then : 

39. 779 -38. 160  =  1. 619°  C. 

The  potentiometer  balance  corresponding  to  a  certain  temperature  difference 
has  now  been  obtained  for  each  of  the  several  thermal  junctions,  and  this 
temperature  difference  accurately  determined  by  means  of  the  two  mercury 
thermometers.  A  knowledge  of  the  relation  between  these  two  quantities 
(1)  potentiometer  balance  and  (2)  temperature  difference,  is  the  sole  object 
of  calibrating.  This  relation  was  determined  for  a  number  of  temperature 
differences  and  the  results  expressed  in  a  number  of  curves,  one  for  each 
junction.  These  curves  are  very  nearly  straight  lines  for  the  range  and  pre- 


-See  p.  23. 


METHODS   AND   APPARATUS. 


27 


cision  used.  Slight  differences  will  be  noted  among  the  several  junctions  in 
the  calibrations  given.  These  are  not  due  to  experimental  error,  as  the 
figures  reproduce  themselves  very  well;  the  cause  is  probably  to  be  found  in 
a  slight  inhomogeneity  of  the  constantan  wire  at  the  different  junctions.  In 
actual  experimenting  the  potentiometer  balance  is  obtained,  and  by  means 
of  the  calibration  curves  just  described  the  corresponding  value  of  the  tem- 
perature difference  can  at  once  be  found. 

A  SAMPLE  BODY-TEMPERATURE  EXPERIMENT. 

In  an  experiment  the  junctions  are  placed  at  the  different  points  where 
it  is  desired  to  obtain  the  temperature,  being  held  in  position  when  necessary 
by  a  strap  or  bandage.  The  apparatus  is  then  operated  in  the  manner  pre- 
viously described,  so  as  to  obtain  data  for  computing  the  temperatures  at 
the  various  points  every  5  or  10  minutes,  as  the  rate  of  temperature  change 
seems  to  require.  A  few  observations  from  an  actual  experiment  are  given 
in  table  3,  in  which  are  noted:  First,  the  time;  next,  an  occasional  balancing 
of  the  current;  then  the  potentiometer  readings  for  the  various  junctions, 
each  reading  consisting  of  a  setting  and  a  deflection  as  already  described. 
After  these  follows  an  occasional  reading  of  the  Beckmann  thermometer  in 
the  constant-temperature  oven.  Finally  a  column  is  provided  for  miscella- 
neous remarks,  including  observations  for  extraneous  electromotive  force,  etc. 

TABLE  3. — Body-temperature  experiment. 
Date:  March  1,  1911.    Subject:  C.  H.  H. 


Time. 

Current 
balance. 

Potentiometer  readings. 

Con- 
stant 
oven- 
tem- 
pera- 
ture 
read- 
ing. 

Notes. 

Junction  A, 
Deep1  rectum. 

Junction  8. 
Shallow'  rectum. 

Junction  C, 
Left  axilla. 

Junction  D, 
Mouth. 

Setting. 

Defl. 

Setting. 

Defl. 

Setting. 

Defl. 

Setting 

Defl. 

P.M. 

lhll» 
16 
21 
26 

ohms 
....... 

ohms 
34.0 
34.0 
34.0 
34.0 

mm. 
-2 
±0 
+  1 
+3 

ohms 
34.0 
34.0 
34.0 
34.0 

mm. 
-3 
-3 
-1 
±0 

ohms 
37.0 
37.0 
37.0 
36.0 

mm. 
+1 
+3 
+8 
-3 

ohms 
37.0 
36.0 
35.0 
35.0 

mm. 
+6 
+5 

-2 

3.07 

Stray 
defl.= 
+2  mm. 

'Junction  about  11  cm.  deep  in  the  rectum.        function  about  7.5  cm.  deep  in  the  rectum. 
COMPUTATIONS   FOR   THE   EXPERIMENT. 

The  method  of  obtaining  the  temperatures  at  the  different  locations  and 
times  specified  involves  very  much  the  same  type  of  computation  as  that  used 
in  calibrating.1  The  corrected  potentiometer  balance  is  obtained  exactly  as 
in  the  calibration  computations  by  adding  two  quantities  to  the  setting:  First, 
the  correction  for  extraneous  electromotive  force;  and  second,  the  deflection 
which  has  been  multiplied  by  a  factor  depending  on  the  galvanometer  sensi- 


'See  p.  25, 


28 


TEMPERATURE    FLUCTUATIONS   IN    THE   HUMAN   BODY. 


tiveness.  Having  determined  the  corrected  potentiometer  balance,  the 
temperature  difference  between  the  two  junctions  is  found  at  once  by  refer- 
ence to  the  calibration  curves,  where  the  relation  between  these  two  quantities 
is  shown.  The  oven-temperature  is  computed  to  the  nearest  hundredth 
from  the  reading  of  the  Beckmann  thermometer.  The  body-temperature  in 
any  particular  case  is  then  found  by  subtracting  the  temperature  difference 
from  the  temperature  in  the  constant  oven.  The  computations  by  means 
of  which  the  various  temperatures  in  the  foregoing  sample  experiment  were 
obtained  are  given  in  table  4. 

TABLE  4. — Computations  for  the  experiment. 
Date:  March  1,  1911.    Subject:  C.  H.  H. 


Time. 

Corrected  potentiometer  balance. 

A 

B 

P.M. 
lhjl» 

21 
26 

lhllm 
16 
21 
26 

ohms 
34.0+2X.04+2X.08  =  34.2 
34.0+2X.04+0          =34.1 
34.  0+2X.04-1X.  08  =  34.0 
34.0+2X.04-3X.08  =  33.9 

ohms 
34.0+2X.04+3X.08  =  34.3 
34.0+2X.04+3X.08  =  34.3 
34.0+2X.04+1X.08  =  34.2 
34.0+2X.04+0          =34.1 

C 

D 

ohms 
37.  0+2X.04-1X.  08  =  37.0 
37.0+2X  .04-3X  .08  =  36.8 
37.0+2X  .04-8X  .08  =  36.4 
36.0+2X.04+3X.08  =  36.3 

ohms 
37.0+2X.04-6X.( 
36.0+2X.04-5X.( 
35.0+2X.04+4X.( 
35.0+2X.04+2X.( 

)8  =  36.6 
)8  =  35.7 
)8  =  35.4 
)8  =  35.2 

Time. 

Temperature  difference                                                                     Body-temperature, 
(from  curves). 

1 

A 

B 

C 

Oven-temperature.       j 

D                                                     Deep 

i  rectum. 

B 

Shallow 
rectum. 

C              D 
arilla.      Mouth' 

P.M. 

lhll"> 
16 
21 
26 

3.13 
3.12 
3.11 
3.10 

3.16 
3.16 
3.15 
3.14 

3.43 
3.41 
3.38 
3.37 

o/"i                               ofi                                   os~i 

3.38     37.29+1.01X3.07     37.26 
3.30     =40.39                       37.27 
3.27    37  28 

37.23 
37.23 
37.24 
37.25 

°c      °c 

36.96    37.01 
36.98    37.09 
37.01     37.12 
37.02    37.14 

3.25   37  29 

i                                  | 

PRECISION  OF  MEASUREMENT. 

To  meet  the  approximate  demands  of  a  precision  discussion,  the  potenti- 
ometer balance  may  be  assumed  as  directly  proportional  to  the  temperature 
difference  between  the  hot  and  cold  thermal  junctions;  hence  the  relation 
between  the  two  can  be  expressed  by  a  single  factor,  rather  than  by  a  curve. 
An  approximate  value  of  this  factor,  by  which  the  potentiometer  balance 
should  be  multiplied  to  give  the  temperature  difference,  is  0.094, 


METHODS   AND   APPARATUS.  29 

The  body-temperature  would  then  be  expressed  by  the  formula: 

Tu=T0-BF 
in  which 

Tu  =  unknown  temperature 
TO   =  oven-temperature 
B    =  potentiometer  balance 

F     =  factor  showing  relation  between   potentiometer  balance   and 
temperature  difference. 

Assume  in  an  average  case:  T0  =  40°  C.,  B  =  32,  and  F  =0.094.  This 
will  give  for  Tu  a  value  of  40-0.094  X  32  =  37°  C. 

The  precision  of  the  various  factors  is  determined  as  follows  :  T0  is  the  oven 
temperature  as  read  during  the  course  of  an  experiment,  and  has  been  shown 
in  a  previous  paragraph  to  be  expressed  by  the  formula: 

TO=A+KR 

where 

A  =  zero  point  of  thermometer,  which  has  been  determined  to  at 

least  0.01°  C. 
K  =  1.01  =  constant 
R   =  reading,  taken  to  the  nearest  0.01°  C. 

B,  the  potentiometer  balance,  is  determined  in  the  last  place  by  deflection, 
which  is  read  to  the  nearest  half-division.  The  sensitiveness  of  the  galva- 
nometer in  this  case  is  such  that  a  deflection  of  1  division  corresponds  to  a 
change  in  B  of  0.072  ohm.  Hence  the  average  deviation  in  B  is  0.036  ohm. 

F  is  obtained  by  calibration.  In  calibrating,  the  following  data  are  ob- 
tained: Toi,  the  oven  temperature,  which  may  be  taken  as  40°  C.;  Tfi,  the 
temperature  in  the  calibrating  flask,  for  instance,  37°  C.  ;  and  Bi,  the  potenti- 
ometer balance,  32.  From  these  the  quantity  F—  (Toi  —  Tfz)  -r-Bi  is  com- 
puted. In  calibrating,  the  temperatures  are  taken  more  precisely  than  in  an 
experiment,  and  this  involves  not  only  a  closer  reading,  but  a  better  deter- 
mination of  the  zero  point  of  the  thermometers.  As  a  matter  of  fact  the 
reading  is  taken  to  0.002°  C.;  and  the  zero  known  to  0.003°  C.  Therefore  we 
may  say,  similarly  to  the  above,  Toi  =A'+K'R'  and  Tfi  =A"  +K"R",  where 
A'  and  A"  are  known  to  0.003°C.;  K'  and  K"  are  constants;  and  R'  and  R" 
are  known  to  0.002°C.  BI,  like  B,  is  known  to  0.036. 

The  complete  expression  for  the  unknown  temperature  is  then  as  follows: 


The  average  deviations  of  the  variables  are  : 

A,   a.d.  =  0.01;         R,     a.d.  =  0.01;         B,    a.d.  =  0.036;       A',  a.d.=  0.003; 
Rr,  a.d.  =0.002;       A",  a.d  =  0.003;       R",  a.d.  =  0.002;       Blt  a.d.  =  0.036. 

The  constants  K,  K',  and  K"  each  have  the  value  1.01. 


30  TEMPERATURE   FLUCTUATIONS   IN   THE   HUMAN    BODY. 

The  effect  on  the  final  result  of  the  deviation  in  each  component  is  obtained 
by  the  aid  of  the  differential  calculus.     Adopting  the  usual  notation: 

AA    =0.01  A/2  =K  X0.01  =  0.01 


32 


„  "DT^t 

AA'    =       X  0.003  =  0.003  A#'  =  -  -  X0.002  =  0.002 

BI  &i 

A?  TIK" 

AA"  =  -  X  0.003  =  0.003  Afi"  =  —  X0.002  =  0.002 


32 

The  deviation  in  the  final  result  will  then  be 

A  =  V(.Ql)*  +  (.Ol)2  +  (.0034)2  +  (.003)2  +  (.002)2  +  (.003)2  +  (.002)2  +  (.0034)  2 

=  0.016°  C. 

It  is  thus  seen  that  the  deviation  expected  in  the  body-temperature, 
caused  by  the  deviations  in  the  various  components,  is  0.016°  C.;  that  is,  each 
temperature  is  measured  to  0.01°  or  0.02°  C.  It  should  be  remembered, 
moreover,  that  the  primary  object  of  this  study  is  to  determine  the  temper- 
ature differences  between  different  points  of  the  body  rather  than  the  absolute 
temperatures.  A  number  of  circumstances  can  be  conceived  which  might 
cause  an  error  in  the  absolute  determination  of  temperature,  but  which  would 
be  without  effect  on  the  difference  "between  two  temperatures.  The  results 
stated  therefore  are  regarded  as  singularly  good. 

LATER  MODIFICATION  OF  THE  APPARATUS. 

After  the  conclusion  of  this  research,  it  was  desired  to  extend  the  application 
of  the  apparatus  to  the  determination  of  the  rectal  temperatures  of  subjects 
in  the  respiration  calorimeters  installed  in  this  laboratory.  It  was  thought 
undesirable,  however,  to  reserve  the  Wolff  potentiometer  for  this  special 
work,  as  to  do  so  would  preclude  its  being  used  for  any  other  measurements; 
therefore  a  special  potentiometer  for  body-temperature  measurements  has 
been  constructed.  The  circuit  arrangement  of  this  instrument  is  somewhat 
different  from  the  ordinary  potentiometer,  and  was  suggested  informally 
to  one  of  the  writers  by  Dr.  Walter  P.  White,  of  the  Geophysical  Laboratory 
of  the  Carnegie  Institution  of  Washington  in  Washington,  D.  C.  It  is  a 
pleasure  here  to  acknowledge  our  indebtedness  to  Dr.  White,  whose  unusual 
experience  with  thermal  junctions  made  his  suggestions  doubly  valuable. 

The  new  arrangement  completely  removes  all  sliding  contacts  from  the 
galvanometer  circuit  and  thus  frees  this  important  circuit  from  the  thermal 
electromotive  forces  which  are  developed  by  the  usual  type  of  sliding  contact. 
An  elementary  diagram  of  the  apparatus  is  shown  in  fig.  6.  The  battery  B 


METHODS   AND  APPARATUS. 


sends  a  current  through  the  circuit  B-P-D-R-A-B,  this  current  being  meas- 
ured by  the  ammeter  A.  The  contact  P  may  be  moved  until  the  fall  in 
potential  along  P-D,  due  to  the  battery  current,  is  just  equal  to  the  voltage 
of  the  thermal-junction  system  TT.  When  this  condition  is  fulfilled — as 
indicated  by  the  absence  of  a  galvanometer  deflection — the  voltage  of  the 
thermal-junction  system  maybe  computed  directly  from  the  constants  of 
the  apparatus.  As  before,  however,  the  temperature  difference  between  the 
junctions  rather  than  their  voltage  is  desired;  and  this  may  be  obtained  in 
the  usual  way  by  calibration. 

The  complete  wiring  diagram  is  shown  in  fig.  7.     It  will  be  noticed  that,  as 
in  the  older  type  of  apparatus,  the  ammeter  A  is  replaced 
by  a  standard  cell  N  and  galvanometer;  also  a  variable 
resistance  V  is  included  in  the  main  circuit  for  adjusting 
the  current  always  to  approximately  the  same  value;1  and 
the  galvanometer  is  provided  with  a  number  of  switches 
by  means  of  which  it  may  be  connected  to  any  one  of  a 
series  of  thermal-junction  pairs,  or  to  the  standard  cell 
circuit.     The  circuit  has  a  great  many  features  in  common 
with  that  of  the  earlier  apparatus  previously  described  in 
detail,2  and  these  need  not  be  considered  again  at  this 
point.     Some  differences,  however,  will  be  noted.     The 
galvanometer  sensitiveness  is  independent  of  the  position 
of  the  contact  P,  since  moving  this  contact  in  no  way 
affects  the  resistance  of  the  galvanometer  circuit.     The 
sensitiveness  being  constant,  a  resistance  W  has  been 
inserted  in  the  galvanometer  circuit,  and  by  this  means 
the    sensitiveness    adjusted    until    the    deflection    reads 
directly  in  hundredths  of  a  degree.     No  special  provision 
is  made  for  reversing  B  and  N,  as  experience  with  the 
earlier  apparatus  showed  this  to  be  unnecessary.     The 
new  apparatus  differs  from  the  old,  also,  in  that  the  ther- 
mometer must  be  detachable.     Two  heavy  wires  have 
therefore  been  run  to  two  metal  blocks  in  each  calorimeter, 
and  to  these  the  thermometer  can  easily  be  attached.    It  will  be  noted  in  fig.  7 
that  each  calorimeter  is  not  provided  with  an  entirely  independent  set  of 
connections,  but  that  the  chair  calorimeter  and  calorimeter  No.  4  are  connected 
in  parallel,  as  are  also  calorimeters  Nos.  3  and  5.     This  is  allowable  because 
other  considerations  prevent  the  calorimeters  thus  joined  from  ever  being 
used  at  the  same  time. 

'It  will  be  seen  that  the  method  as  described  is  approximate  only,  and  not  exact,  since  the 
measuring  current  changes  with  each  position  of  P.  The  error  thus  introduced  may  be  made 
negligibly  small  for  any  case  by  making  R  sufficiently  large  as  compared  with  CD.  The 
resistance  CD  should  be  kept  small  from  another  standpoint  as  well,  namely,  that  of  sensi- 
tiveness. By  the  use  of  some  kind  of  compensating  resistance,  equal  to  CD  and  arranged 
so  as  to  be  decreased  as  CD  is  increased,  and  vice-versa,  the  arrangement  can  be  made  exact. 

'See  pp.  14-22. 


FIG.  6.  Elementary  wir- 
jng  diagram  of  mod- 
ified apparatus.  Cur- 
rent from  the  battery 
B  flows  through  PD, 
this  being  part  of  the 
slide  wire  CD,  then 
through  the  resistance 
R  and  finally  returns 
to  the  battery  through 
the  ammeter  A.  The 
thermal  junction  sys- 
tem TT  is  connected 
through  the  galvan- 
ometer G  to  the  points 
C  and  D,  this  circuit 
being  free  from  sliding 
contact. 


32 


TEMPERATURE    FLUCTUATIONS   IN   THE   HUMAN    BODY. 


The  apparatus  is  designed  to  measure  temperatures  to  0.02°  C.,  and  has 
a  range  of  8°  C.     The  voltage  of  the  cell  B  is  1.4  volts;  that  of  N,  1.0197  volts. 


VWVWWWWVi 
O 


CALORIMETERS 
BED        CHAIR          N0.3  NO.4 


NO.5 


OVEN 


Fia.  7.  Complete  wiring  diagram  of  modified  apparatus.  Current  from  the  battery  B  flows  through 
a  portion  (PD )  of  the  slide  wire  CD,  then  through  the  resistances  V  and  R,  and  returns  to  the 
battery  through  the  resistance  M.  The  points  C  and  D  are  connected  without  sliding 
contact  to  the  switching  arrangement,  of  which  G2  connects  the  galvanometer  G  in  circuit,  T 
replaces  the  thermal  junction  system  when  testing  and  1 ,  2,  and  3  are  connected  to  thethermal 
junctions  in  the  calorimeters  and  the  constant-temperature  oven.  The  constantan  wires  are 
indicated  by  the  heavy  lines;  the  calorimeter  thermometers  are  detachable  at  the  small 
circles.  W  is  a  resistance  for  adjusting  the  galvanometer  sensitiveness.  N  is  the  standard 
cell,  protected  by  the  high  resistance  O,  and  connected  to  the  circuit  through  the  double  con- 
tact key  Gi.  The  switch  K  is  for  convenience  in  bringing  the  galvanometer  to  rest. 


METHODS   AND   APPARATUS. 


33 


Copper-constantan  couples  are  used,  as  previously.  The  slide  wire  C-D  has 
a  resistance  of  0.372  ohm,  and  is  divided  into  400  divisions,  each  of  which 
represents  0.02°  C.  temperature  difference;  M  has  a  value  of  about  1200 
ohms;  and  R,  about  400  ohms.  The  maximum  resistance  of  V  is  about  100 
ohms;  this  should  be  variable  in  steps  of  about  1  ohm  each.  The  value  of 
W  has  not  been  measured,  this  resistance  having  been  adjusted  by  trial. 
O,as  before,  is  10,000  ohms.  For  B  a  dry  cell  is  used,  from  which  a  measuring 
current  of  about  0.00086  ampere  is  drawn;  N  is  the  Weston  Standard  cell  used 


Fid.  8.  Detachable  thermometer  for  use  inside  the  calorimeter,  with  connections.    A  and  E  are  of 
constantan;  B  and  F  of  copper. 

previously.  The  potentiometer  C-D  consists  of  a  0.6  millimeter  manganin 
wire,  arranged  in  the  form  of  a  circle,  the  sliding  contact  P  being  operated  by  a 
knob  at  the  center.  The  resistances  M,  R,  V,  and  O  are  of  manganin. 

The  constantan  wire  from  the  constant-temperature  flask  to  the  inside  of 
the  calorimeter  is  2.05  millimeters  in  diameter,  insulated  with  rubber  and 
covered  with  a  protecting  braid.  As  will  be  seen  in  fig.  8,  this  wire  is  soldered 


34  TEMPERATURE   FLUCTUATIONS  IN  THE   HUMAN   BODY. 

at  the  calorimeter  to  a  small  constantan  block  A,  and  in  the  same  way  the 
copper  wire  running  to  the  calorimeter  is  soldered  to  a  small  copper  block  B. 
These  blocks  are  mounted  on  a  hard-rubber  base  C,  and  are  provided  with 
binding  screws  of  constantan  and  copper,  respectively,  by  means  of  which  the 
thermal  junction  may  be  connected  to  the  circuit  without  the  intervention 
of  any  metal  other  than  the  two  required  for  the  thermometer  itself. 

The  thermometer  consists  of  two  wires  1.6  meters  long,  0.0455  millimeters 
in  diameter,  of  constantan  and  copper  respectively,  well  insulated,  and  soldered 
together  at  one  end  D.  At  the  other  end  the  wires  are  screwed  to  two  flat 
terminals  of  constantan  E  and  copper  F,  which  are  shaped  to  be  received  by 
the  binding  screws  already  mentioned.  These  flat  terminals  are  mounted 
on  a  hard-rubber  block  G  to  which  the  wires  are  fastened  in  such  away  as  to 
make  the  joint  absolutely  rigid.  The  wires  are  covered  by  a  6.4  millimeter 
rubber  tube  H  down  to  some  25  centimeters  from  the  junction  itself;  this 
tube  is  protected  by  a  spiral  spring  I  at  the  point  where  it  leaves  the  hard- 
rubber  block  G.  This  comparatively  heavy  tubing  is  continued  by  a  smaller 
thin-walled  rubber  tube  J  for  the  remainder  of  the  distance  to  the  thermal 
junction;  this  thin  tubing  fits  tightly  around  the  wires  and  is  closed  at  the  end 
D  by  being  tied  tightly  with  silk. 

It  should  be  remarked  that  considerable  trouble  has  been  experienced  by 
extraneous  electromotive  forces  developed  at  the  point  where  the  constantan 
wire  from  the  thermal  junction  is  soldered  to  the  flat  constantan  terminal  E. 
This  stray  electromotive  force  has  been  found  to  be  reduced  practically  to 
zero  when  the  soldered  connection  is  replaced  by  a  clamp  connection,  made 
by  fastening  the  wire  under  the  head  of  a  small  constantan  screw,  without 
the  use  of  solder.  Apparently  in  this  case  the  electromotive  force  is  due  not 
to  difference  in  the  constitution  of  the  two  pieces  of  metal,  but  rather  to  the 
unbalanced  effect  of  the  constantan-solder  and  solder-constantan  couples. 
This  leads  to  the  conclusion  that  when  it  is  necesary  to  solder  two  pieces  of 
metal  of  identical  constitution  together,  stray  electromotive  forces  will  be 
less  likely  to  be  developed  if  the  two  pieces  have  the  same  size  and  shape  and 
are  surrounded  by  as  nearly  as  possible  the  same  conditions  of  heat  loss. 

The  operation  of  the  apparatus  is  identical  in  procedure  with  the  earlier 
form.  The  current  is  first  balanced,  after  which  the  potentiometer  balance 
is  found,  partly  by  setting,  partly  by  deflection.  Occasional  observations 
are  also  required  of  the  temperature  in  the  oven  and  the  stray  electromotive 
force. 


DISCUSSION   OF  RESULTS.  35 


PART  III. — DISCUSSION  OF  RESULTS. 

While  this  investigation  was  primarily  undertaken  to  study  simultaneously 
the  temperature  in  different  parts  of  the  body,  many  secondary  points  of 
considerable  importance  were  naturally  encountered  in  the  process  of  the 
investigation. 

THERMAL   GRADIENT    OF    THE    BODY. 

The  method  of  electrical  measurement  here  outlined,  owing  to  its  extreme 
sensitiveness  and  delicacy,  is  admirably  adapted  for  a  study  of  the  thermal 
gradient  of  the  body.  As  has  been  previously  shown,  with  an  internal  body- 
temperature  of  not  far  from  37°  C.  and  a  surface  temperature  of  about  32°  C. 
one  would  expect  normally  a  thermal  gradient.  The  exact  significance  of 
this  gradient  may  be  better  understood  after  a  consideration  of  certain  points 
with  regard  to  the  physical  structure  of  the  body.  If  the  highest  heat  pro- 
duction were  at  the  exact  center  of  the  body  and  there  was  a  definite  thermal 
gradient  from  the  center  to  the  skin,  it  is  obvious  that  the  measurement  of 
body-temperature,  particularly  the  average  body-temperature,  would  present 
almost  insuperable  difficulties.  One  could  not  select  a  point  half-way  between 
the  surface  of  the  skin  and  the  center  of  the  body  and  assume  that  the  tempera- 
ture at  this  point  would  represent  the  average  body-temperature,  since  there 
would  be  no  way  of  obtaining  a  record  of  this  temperature.  On  the  other 
hand,  if  the  thermal  gradient  rose  sharply  for  the  first  few  centimeters  beneath 
the  surface  of  the  skin  and  soon  reached  a  point  beyond  which  the  body 
temperature  was  not  materially  increased,  the  problem  would  be  much  less 
complicated.  If,  as  is  frequently  the  case,  we  desire  to  note  the  total  amount 
of  heat  actually  latent  in  the  body  at  a  given  time,  we  must  know  the  body- 
temperature  as  nearly  as  possible.  Consequently  a  study  of  the  thermal 
gradient  was  first  made. 

METHOD    OF   STUDYING    THE   THERMAL   GRADIENT. 

In  studying  the  thermal  gradient,  the  rectum  was  used  with  men,  and  the 
rectum  and  the  vagina  with  women,  both  being  deep  cavities  into  which  the 
thermal  junctions  could  be  inserted  for  a  considerable  distance.  It  is  obvious 
that  at  the  entrance  of  either  of  these  cavities  the  temperature  will  be  low,  i.  e., 
that  of  the  environment,  but  as  the  thermal  junction  is  inserted  deeper  into 
the  cavity,  the  temperature  more  nearly  approximates  that  of  the  interior 
portion  of  the  body.  The  important  point  to  note,  then,  is  the  depth  of  inser- 
tion required  to  obtain  the  maximum  temperature.  For  this  purpose,  two  ther- 
mal junctions  were  inclosed  in  a  single  tube,  and  bound  together  in  such  a  way 
that  one  was  exactly  3.5  centimeters  from  the  other.  This  tube  was  then 
inserted  in  the  cavity  to  be  studied,  so  that  the  deeper  junction  was  approxi- 
mately 10  centimeters  within  the  cavity  and  the  other  accordingly  6.5  centi- 
meters. Readings  were  taken  until  constancy  had  been  obtained;  then  both 
thermometers  were  withdrawn  to  a  new  location  in  the  cavity,  and  the  meas- 
urement repeated.  By  this  means  the  whole  region  was  studied,  the  two  ther- 


TEMPERATURE    FLUCTUATIONS   IN   THE    HUMAN    BODY. 


mometers  allowing  simultaneous  observations,  each  serving  as  a  check  upon 
the  other.  With  women,  observations  could  be  made  simultaneously  in  the 
rectum  and  the  vagina. 

EXPERIMENTAL   RESULTS. 

The  results  are  expressed  in  the  form  of  curves  (see  figs.  9,  10, 11,  12,  and  13), 
in  which  the  depths  of  insertion  are  expressed  by  horizontal  distances,  the  cor- 
responding temperatures  being  represented  vertically.  The  records  for  rectal 
observations  are  marked  RD  and  Rs  for  the  deep  and  shallow  temperatures 
respectively;  in  a  similar  manner  the  curves  for  the  deep  and  shallow  vagina 
are  designated  by  VD  and  Vs.  In  some  instances,  when  only  a  single  thermom- 
eter was  used  in  either  cavity,  the  subscript  is  naturally  omitted. 

37.2°C 


TABLE  5. — Thermal  gradient  observations. 


01334-56  7CM 

DEPTH 
FIG.  9.  Observations  on  thermal  gradient,  with  Mrs.  B — 1. 

In  the  experiment  represented  by  fig.  9,  observations  were  made  on  a  woman 
(Mrs.  B — 1)  with  one  thermometer  in  the  rectum  and  a  second  in  the  vagina, 
the  double  thermometer  not  being 
used  in  either  case.  The  actual  tem- 
perature observations  are  given  in 
table  5. 

The  results  show  that  at  a  depth  of 
3  centimeters  in  either  cavity  the  tem- 
perature was  over  a  degree  lower  than 
at  a  depth  of  7  centimeters.  The  rise 
was  rather  regular  and  gradual  up  to 
5  centimeters;  beyond  that  point  the 
rise  was  much  slower  and  between  6 


Rectal  thermometer. 

Vaginal  thermometer. 

Insertion. 

Temperature. 

Insertion. 

Temperature. 

cm. 

°c 

cm. 

°c. 

7 

37.20 

7 

37.12 

6 

37.17 

6 

37.11 

5 

36.98 

5 

36.98 

4            36.59      !        4 

36.80 

3 

36.09 

3 

36.00 

and  7  centimeters  it  nearly  ceased,  in- 
dicating that  in  this  case  and  under  the  conditions  of  the  experiment,  the  maxi- 
mum body-temperature  was  reached  when  the  thermometer  was  inserted  G  or 
7  centimeters  in  the  vagina  or  the  rectum. 


DISCUSSION   OF  RESULTS. 


FIG.  10.  Observations  on  thermal  gradient,  with  C.  H.  H. 

In  the  experiment  represented  by  fig.  10,  a  double  thermometer  was  used  in 
the  rectum,  one  of  the  laboratory  assistants  (C.  H.  H.)  serving  as  a  subject. 
It  is  interesting  to  note  from  the  curves  that  between  the  depths  of  0.5  centi- 
meters and  6  centimeters,  there  is  a  difference  in  temperature  amounting  to 
2.72°  C.  The  curves  rise  very  rapidly  until  the  depth  of  4  centimeters  is 
reached,  continuing  to  rise  much  more  slowly  for  the  next  2  centimeters. 
Apparently  with  this  subject  the  temperature  reached  its  highest  point  at  a 


209173 


38 


TEMPERATURE    FLUCTUATIONS   IN   THE   HUMAN   BODY. 


depth  of  about  6  centimeters,  and  from  6  to  12  centimeters  there  was  no  material 
variation. 


37.6°C 

374 

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ft 

£37.2 

o: 
bJ 
CL 
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u 
h 

368 
36.6 

^  — 

___—  -- 

i 

^ 

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^ 

/ 

^- 

VoX" 
S 

7 

0 

23456789                IOCMS. 

DEPTH 
FIG.  11.  Observations  on  thermal  gradient,  with  Mrs.  B— 1. 

The  experimental  results  shown  in  fig.  11  were  obtained  with  the  woman 
subject  previously  mentioned,  a  double  thermometer  being  used  in  the  vagina 
and  a  single  thermometer  in  the  rectum.  The  curves  show  in  a  general  way 
the  characteristics  of  the  curves  in  the  preceding  tests,  although  the  gradient 
is  not  so  sharply  indicated. 


372°C 


4 
DEPTH 


FIG.  12.  Observations  on  thermal  gradient,  with  J.  J.  C. 

A  thermal-gradient  experiment  was  made  with  another  laboratory  assistant 
(J.  J.  C.)  in  which  a  double  thermometer  was  used  in  the  rectum,  the  results 
being  shown  in  fig.  12.  With  this  subject  the  temperature  at  a  depth  of  0.5 


DISCUSSION    OF   RESULTS.  39 

centimeters  was  35.80°  C.,  and  at  8  centimeters  37.03°  C.  No  material  differ- 
ences were  noted  between  6  and  8  centimeters.  As  usual  the  gradient  rose 
very  sharply  up  to  a  depth  of  6  centimeters,  after  which  the  temperature 
remained  practically  constant. 

The  records  for  a  third  experiment  with  the  woman  subject  are  given  in  fig. 
13;  in  this  experiment  a  single  thermometer  was  used  in  the  vagina  and  a 
double  thermometer  in  the  rectum.  The  temperature  rose  very  rapidly  until 
about  5  centimeters  was  reached ;  afterwards  it  remained  essentially  constant 
for  the  remaining  distance  between  5  and  10  centimeters,  beyond  which  point 
it  was  not  studied.  The  temperature  at  2  centimeters  was  about  36.8°  C.  and 
at  10  centimeters  37.3°  C.,  showing  a  difference  of  approximately  0.5°  C. 


37  4  C 

37  a 

UJ 

cc 

^370 

< 
CC 
LJ 
°-  36.8 

UJ 

r- 

36.6 
36.4 

> 

>a  — 

/r 

s 

,—  •—• 

~~~—  < 

£ 

2 

,  —  ' 

y 

2 

'/ 

0  I  334-5678 

DEPTH 

FIG.  13.  Observations  on  thermal  gradient,  with  Mrs.  B— 1. 


10  CMS. 


GENERAL    CONCLUSIONS   WITH    REGARD    TO    THE   THERMAL   GRADIENT. 

It  is  apparent,  therefore,  that  the  thermal  gradient  between  the  temperature 
at  the  surface  of  the  body  and  at  a  depth  of  about  5  centimeters  is  quite  notice- 
able; evidently  beyond  5  centimeters  the  body-temperature  is  essentially  at 
its  maximum.  It  has  been  neither  disproved  nor  shown  by  this  study,  of 
course,  that  the  temperature  may  not  be  actually  higher  in  the  liver  or  in  some 
other  active  organs  of  the  body;  indeed,  it  is  to  be  expected  that  where  there  is 
special  metabolic  activity,  as  in  the  liver  and  other  glands,  there  might  be  a 
somewhat  higher  temperature.  On  the  other  hand,  Rancken  and  Tigerstedt,1 
who  found  that  ordinarily  the  temperature  in  the  stomach  was  about  0.1°  C. 
higher  than  that  in  the  rectum,  were  unable  to  note  any  rise  in  temperature 
during  the  first  hour  of  active  digestion,  except  such  as  was  due  to  the  heat  of 
the  food.  However,  in  finding  the  average  temperature  of  the  human  body, 
it  appears  safe  to  say  that  the  temperature  rises  to  its  highest  point  at  a  depth 
of  6  to  7  centimeters. 


'Rancken  and  Tigerstedt,  Biochcm.  Zeitsch.,  1C08,  11,  p.  36. 


40  TEMPERATURE   FLUCTUATIONS   IN   THE   HUMAN    BODY. 

From  the  very  sharp  gradient,  it  may  be  easily  inferred  that  the  surface 
temperatures  of  the  body,  or  those  slightly  below  the  surface,  are  liable  to  the 
greatest  errors  in  determination,  and  consequently,  as  ordinarily  measured, 
they  can  have  but  little  physiological  significance. 

SELECTION  OF  LOCALITIES  FOR  SIMULTANEOUS  MEASUREMENT 
OF  FLUCTUATIONS  IN  BODY-TEMPERATURE. 

NATURAL   CAVITIES. 

The  rectum  and  the  vagina  used  alone  are  not  especially  suitable  for  study- 
ing the  constancy  or  the  lack  of  constancy  of  temperature  fluctuations  in 
different  parts  of  the  body,  since  these  two  cavities  are  side  by  side.  Unfortu- 
nately no  other  cavity  presents  such  ideal  conditions  for  the  study  of  fluctua- 
tions in  body-temperature  as  do  these,  the  only  other  openings  which  could  be 
used  being  the  mouth  and  the  oesophagus.  While  it  has  long  been  the  custom 
of  physicians  and  physiologists  to  take  temperatures  in  the  mouth,  certain 
grave  objections  have  been  raised  to  the  use  of  this  locality,  and  it  is  obvious 
that  a  more  careful  study  of  buccal  temperature  should  be  made  before  rely- 
ing upon  this  cavity  for  exact  temperature  measurements.  Accordingly, 
a  considerable  amount  of  experimenting  was  done  in  connection  with  this 
research  to  test  the  reliability  of  temperatures  taken  in  the  mouth. 

TEMPERATURE   MEASUREMENTS   IN  THE   MOUTH. 

A  variety  of  methods  were  used  for  taking  mouth  temperatures,  but  even 
when  extreme  care  was  observed,  the  results  were  unsatisfactory.  The  experi- 
ment was  tried,  for  instance,  of  inserting  a  thermal  junction  beneath  the 
tongue  and  recording  the  temperature  until  it  became  constant;  the  thermal 
junction  was  then  withdrawn  and  immediately  replaced  by  a  carefully  cali- 
brated clinical  thermometer1  which  was  allowed  to  remain  in  position  for  5 
minutes.  The  temperatures  indicated  by  the  two  measurements  were  not 
identical,  the  thermal  junction  giving  results  0.2°  to  0.4°  F.  lower.  Again,  the 
mercurial  thermometer  and  the  thermal  junction  were  fastened  together  and 
inserted  beneath  the  tongue  for  a  period  of  possibly  20  minutes,  the  thermal 
junction  being  read  at  regular  intervals  until  a  maximum  was  reached,  this 
requiring  some  15  minutes.  When  the  maximal  reading  was  compared  with 
the  clinical  thermometer  reading  it  was  found  to  be  0.1°  to  0.3°  F.  lower  than 
the  latter. 

This  continual  disagreement  led  to  a  doubt  as  to  the  wisdom  of  using  this 
locality  for  taking  temperature  records,  and  of  the  clinical  thermometer  as  a 
standard.  As  a  further  test,  the  experiment  was  then  tried  of  tying  two 
clinical  thermometers  together,  inserting  them  in  the  mouth,  and  removing 
them  at  the  end  of  5  minutes  to  take  the  records.  After  the  thermometers 
had  been  shaken  down,  they  were  replaced  in  the  mouth  and  further  5-minute 

'Inasmuch  as  the  Fahrenheit  degree  is  employed  in  graduating  practically  all  of  the 
mercurial  clinical  thermometers  used  in  this  country,  this  unit  is  made  the  basis  of  the 
discussion  of  buccal  temperatures,  although  in  all  other  sections  of  the  report  the  centigrade 
scale  is  regularly  used. 


DISCUSSION    OF   RESULTS. 


41 


records  taken.  For  approximately  10  minutes  the  readings  of  the  two  ther- 
mometers disagreed;  afterwards  they  were  identical.  This  led  to  the  belief 
that  unequal  conditions  of  heat  loss  caused  the  discrepancies  observed  in  the 
earlier  readings.  To  equalize  this  heat  loss,  warm  water  was  held  in  the  mouth 
and  simultaneous  records  taken  with  the  thermal  junction  and  the  clinical 
thermometer,  the  water  acting  in  a  way  as  a  protection  from  outside  tempera- 
ture influences.  The  results  showed  the  thermal  junction  in  one  instance  to 
have  the  same  maximal  temperature  as  the  clinical  thermometer,  but  usually 
it  was  0.2°  to  0.3°  F.  lower.  Then  the  thermal  junction  was  embedded  in 
paraffin,  and  its  records  compared  with  those  of  the  clinical  thermometer. 
The  results  showed  that  even  under  these  conditions  the  thermal  junction 
readings  ranged  from  0.1°  higher  to  0.3°  F.  lower  than  those  of  the  clinical 
thermometer. 


98.6°F 

=,8.4 

98.2 

98.0 

97.8 

97.6 

97.4 

97.3 


MINUTES 

F.  14.  Observations  showing  the  rise  of  temperature  in  the  mouth. 
(I)  clinical  thermometer,  (II)  thermal-junction  thermometer. 

Finally  the  design  of  the  thermal  junction  was  changed.  In  all  of  the 
previous  experimenting  with  the  mouth  temperature,  a  junction  of  either  type 
A  or  C  (fig.  3)  was  used.1  The  new  junction  was  built  with  a  heavy,  pear- 
shaped,  copper  element,  the  bulb  of  which  was  about  1  centimeter  in  diameter. 
The  constantan  element,  a  small  wire,  was  soldered  to  the  copper  at  about  the 
center  of  the  bulb,  by  means  of  a  small  hole  drilled  through  to  this  point. 
This  junction  was  then  compared  with  the  clinical  thermometer,  as  in  the 
previous  experiments.  The  results  obtained  from  six  comparisons  show  that 
the  thermal  junction  and  clinical  thermometer  agreed  in  three  cases,  the 
thermal  junction  was  0.1°  F.  higher  than  the  clinical  thermometer  in  two 
cases,  and  0.2°  F.  higher  in  the  remaining  case. 


'See  p.  18. 


42  TEMPERATURE   FLUCTUATIONS   IN    THE   HUMAN    BODY. 

Two  curves  are  reproduced  in  fig.  14,  showing  records  obtained  in  the  mouth 
with  a  clinical  thermometer  and  with  a  thermal-junction  thermometer.  In 
these  curves  the  intervals  of  time  during  which  the  thermometer  was  held  in 
the  mouth  are  expressed  by  horizontal  distances,  the  corresponding  tempera- 
tures being  represented  vertically. 

Curve  I  may  be  of  interest  in  showing  that  a  clinical  thermometer  inserted 
beneath  the  tongue  does  not  attain  its  maximal  temperature  for  a  considerable 
time.  The  curve  was  obtained  in  the  following  way:  A  subject  carefully 
trained  to  the  use  of  a  clinical  thermometer,  after  preparing  for  the  experiment 
by  keeping  his  mouth  closed  for  perhaps  10  minutes,  seated  himself  and  placed 
a  clinical  thermometer  beneath  the  tongue,  allowing  it  to  remain  for  15 
seconds.  He  then  removed  the  thermometer,  read  it,  quietly  shook  it  down, 
and  replaced  it,  this  time  for  30  seconds.  This  procedure  was  repeated,  the 
thermometer  being  kept  in  place  during  constantly  increasing  periods  of  time 
up  to  13  minutes.  Even  after  the  thermometer  had  been  inserted  7  minutes, 
a  further  rise  of  over  0.1°  F.  was  noted;  this,  it  would  seem,  must  have  been 
caused  by  the  slowness  of  the  cavity  in  warming  up,  as  the  true  body-temperature 
must  have  been  slowly  falling  on  account  of  the  quietness  of  the  subject. 

Curve  II  was  obtained  shortly  afterwards  with  the  thermal  junction;  in 
this  case,  however,  the  procedure  was  greatly  simplified.  The  thermometer 
was  inserted  at  a  definite  instant  and  its  temperature  taken  each  minute  by 
means  of  the  usual  measuring  apparatus.  The  curve  is  similar  in  shape  to  that 
obtained  with  the  clinical  thermometer;  the  maximal  temperature  indicated 
is,  however,  somewhat  lower. 

Having  obtained  such  inconstant  results  in  the  mouth  with  these  two  types 
of  thermometers,  an  attempt  was  made  to  find  out  if  better  comparisons  could 
not  be  obtained  in  the  rectum.  The  experiment  was  accordingly  tried  of 
inserting  the  thermal  junction  about  7  centimeters  into  the  rectum,  taking 
readings  for  perhaps  15  minutes  until  constancy  was  assured,  then  removing 
the  thermometer  and  replacing  it  by  a  clinical  thermometer  inserted  to  the 
same  depth.  The  results  given  by  the  thermal  junction  varied  from  0.1°  F. 
lower  to  0.2°  F.  higher  than  the  clinical  thermometer. 

When  the  thermal  junction  and  the  clinical  thermometer  were  fastened 
together  in  a  single  rubber  tube  and  inserted  in  the  rectum,  the  maximal 
reading  of  the  thermal  junction  in  one  case  was  identical  with  that  of  the 
clinical  thermometer,  while  in  another  instance  it  was  0.2°  F.  lower  than  the 
clinical  thermometer.  This  pointed  to  an  error  in  the  thermal- junction  reading, 
but  a  further  test  was  made  which  showed  that  the  reading  of  the  clinical  ther- 
mometer was  by  no  means  an  indisputable  standard.  In  this  test,  two 
carefully  calibrated  clinical  thermometers  were  inserted  in  a  rubber  tube  and 
placed  in  the  rectum.  After  10  minutes  they  were  withdrawn,  carefully 
removed  from  the  tube,  and  read.  The  readings  were  not  identical,  but 
disagreed  by  0.1°  to  0.2°  F. 

In  order  to  make  sure  that  the  presence  of  the  rubber  tubing  did  not  vitiate 
the  results,  a  thermal  junction  and  a  clinical  thermometer  were  inclosed  in 


DISCUSSION    OF   RESULTS.  43 

rubber  tubing  exactly  as  for  an  experiment.  They  were  then  immersed  in  a 
bath  of  warm  water  and  readings  were  taken  continuously  of  the  thermal  junc- 
tion temperature;  at  the  end  of  10  minutes,  they  were  withdrawn  from  the 
water,  the  tubing  removed,  and  the  clinical  thermometer  read.  In  one  test,  at 
a  temperature  of  98°  F.,  the  reading  of  the  clinical  thermometer  agreed  exactly 
with  the  record  obtained  with  the  thermal  junction;  in  a  second  test,  at  a 
temperature  of  about  99.4°  F.,  the  records  disagreed  by  0.4°  F.  Shortly  after- 
wards the  clinical  thermometer  used  was  broken,  so  that  this  result  could  not 
be  verified. 

Although  no  definite  conclusion  was  reached,  these  comparison  experiments 
left  in  the  minds  of  the  experimenters  grave  doubts  as  to  the  feasibility  of 
using  the  mouth  in  temperature  observations,  and  also  an  indefinite  distrust 
of  the  clinical  thermometer  for  accurate  work.  It  should  be  stated  that  a 
type  of  mercurial  thermometer  was  used  that  probably  represented  as  good 
an  instrument  as  is  ordinarily  available,  selection  being  made  from  a  number 
of  thermometers  that  had  been  simultaneously  calibrated.  It  is  evident  that 
the  rise  of  mercury  in  the  thread  in  a  series  of  impulses  may  easily  lead  to 
errors  as  great  as  0.2°  F.,  and  hence  whatever  value  the  mercury  self-register- 
ing thermometer  has  to  the  clinician,  it  can  have  little,  if  any,  value  when 
accurate  body-temperature  measurements  are  desired. 

ARTIFICIAL  CAVITIES. 

In  the  effort  to  find  favorable  places  for  making  temperature  observations, 
certain  artificial  cavities,  such  as  the  closed  axilla  or  groin,  or  between  the 
closed  hands,  were  carefully  studied.  These  so-called  cavities  are  really 
more  or  less  exposed  portions  of  the  skin,  the  configuration  of  which  has  been 
changed  so  as  to  form  a  closed  pocket.  On  account  of  the  large  amount  of 
subcutaneous  fat,  greater  possibilities  for  finding  such  cavities  are  afforded 
with  women  than  with  men;  accordingly,  in  experiments  with  a  woman 
attempts  were  made  to  study  the  temperature  fluctuations  by  means  of  a 
thermometer  placed  between  the  arm  and  the  breast,  between  the  two  breasts, 
and  in  different  parts  of  the  body  more  or  less  inclosed  by  flesh. 

The  one  great  difficulty  with  all  of  these  so-called  artificial  cavities  is  that 
they  require  considerable  time  to  warm  them  to  the  maximum  temperature. 
The  temperature  of  the  exposed  skin  before  the  cavity  is  made  may  be  as  low 
as  32°  C.,  while  that  in  the  inclosed  cavity,  equilibrium  having  once  been 
established,  may  be  36°  or  37°  C.  At  the  beginning  of  a  test,  therefore,  the 
cavity  will  have  a  temperature  not  far  from  32°  C.,  and  will  gradually  become 
warmed  to  36°  C.  or  thereabouts,  before  it  can  be  used  for  comparison  with 
natural  cavities,  such  as  the  rectum  and  the  vagina.  The  warming-up  period 
usually  occupies  20  or  30  minutes  for  the  axilla,  the  length  of  the  period 
depending  principally  on  the  closure  obtained.  For  the  cavities  made  by  the 
groin  and  by  the  hands,  the  preliminary  warming  period  is  even  longer,  since 
these  cavities  are  formed  from  places  ordinarily  less  inclosed  than  the  axilla. 
To  avoid  this  loss  of  time,  a  hot-water  bottle,  previously  filled  with  water  at 


44  TEMPERATURE   FLUCTUATIONS   IN   THE   HUMAN   BODY. 

a  temperature  2°  or  3°  C.  higher  than  that  of  the  body,  was  placed  in  the 
inclosed  portion  for  5  minutes  before  inserting  the  thermometer.  By  this 
means  the  cavity  was  preheated  to  approximately  normal  temperature,  and 
came  to  its  final  value  in  about  half  of  the  time  previously  required. 

SIMULTANEOUS  OBSERVATIONS  OF  BODY-TEMPERATURE  IN 
DIFFERENT  LOCALITIES. 

From  the  previous  discussion  of  the  thermal  gradient  it  is  obvious  that  it 
would  be  practically  impossible  to  determine  the  average  temperature  of  the 
human  body,  although  as  a  gradient  effect  is  most  marked  in  the  last  peripheral 
4  centimeters  of  body  material,  a  large  portion  of  the  body  would  have  a  tem- 
perature not  far  from  that  of  the  rectum.  Fortunately,  for  purposes  of  calorim- 
etry,  what  is  chiefly  desired  is  the  fluctuations  in  temperature  from  hour  to 
hour  or  from  day  to  day.  One  must  be  sure  that  the  fluctuations  in  tempera- 
ture throughout  the  whole  body  are  of  equal  value,  since  otherwise  no  accurate 
estimate  can  be  made  of  the  total  heat  gained  or  lost  due  to  a  rise  or  fall  in 
temperature. 

The  temperature  of  the  body  rarely  remains  constant,  even  for  so  short  a 
time  as  10  minutes;  this  was  shown  by  a  series  of  observations1  made  every  4 
minutes  for  several  days  in  which  practically  no  two  consecutive  readings  were 
exactly  alike.  The  normal  temperature  rhythm,  with  a  maximum  between  4 
and  5  o'clock  in  the  afternoon  and  a  minimum  between  2  and  5  o'clock  in  the 
morning,  is  considerably  accentuated  by  a  number  of  extraneous  factors,  but 
even  with  the  subject  lying  in  bed  without  food,  or  with  a  small  amount  of  food, 
the  range  in  temperature  in  24  hours  may  be  as  high  with  a  normal  subject 
as  1.3°  C.  (2.3°  F.). 

In  the  collected  results  of  body-temperature  measurements  obtained  in  a 
large  number  of  experiments  with  the  respiration  calorimeter  at  Wesleyan 
University,  Benedict  and  Carpenter2  report  that  the  average  body-temperature 
in  experiments  with  food  was  36.82°  C.  (98.3°  F.),  the  minimum  being  35.67°  C., 
and  the  maximum,  38.23°  C.  The  average  range  for  all  of  the  experiments 
was  0.96°  C.,  the  minimum  range,  0.44°  C.,  and  the  maximum,  1.64°  C.  In  a 
series  of  experiments  with  11  subjects  in  which  food  was  not  taken,  covering  in 
all  31  days  of  24  hours  each,  the  average  temperature  of  the  subjects  was 
36.67°  C.  (98°  F.).  The  minimum  temperature  observed  was  35.53°  C.,  and 
the  maximum,  37.74°  C.  The  average  range  in  temperature  was  0.77°  C.,  the 
minimum  range  being  0.38°  C.,  and  the  maximum,  1.36°  C.  (2.45°  F.). 

The  large  number  of  observations  made  on  body-temperature  by  electrical 
methods  in  the  last  few  years  have  shown  that  there  are  fluctuations  aside 
from  the  normal  rhythm — fluctuations  that  can  be  produced  artificially;  for 
example,  changing  from  a  lying  to  a  sitting  position  will  cause  a  slight  rise  in 
temperature,  as  will  also  the  taking  of  hot  drinks  or  hot  food.  Eating  a  meal 
may  cause  a  rise  of  as  much  as  0.15°  C.  in  20  minutes,  and  severe  muscular 

'Benedict  and  Snell,  Archiv  f.  d.  ges.  Physiol.,  1902,  90,  p.  33. 

'Benedict  and  Carpenter,  Publication  No.  126,  Carnegie  Institution  of  Washington, 
1910,  p.  121. 


DISCUSSION    OF   RESULTS. 


45 


TABLE  6. — Age,  height,  and  weight  of 
subjects. 


work  as  much  as  0.50°  C.  in  30  minutes.  In  fact,  any  increase  in  body  activity 
tends  to  increase  the  temperature.  On  the  other  hand,  muscular  relaxation 
and  sleep,  as  well  as  cold  water  and  cold  food,  will  cause  a  fall  in  temperature. 
Consequently,  in  certain  of  our  experiments  the  effort  was  made  by  various 
means  to  produce  artificially  these  fluctuations  in  temperature  in  order  to 
enable  us  to  secure  better  conditions  for  measurements  of  temperature  fluctua- 
tions in  different  parts  of  the  body. 

The  24  experiments  in  this  study  of  body-temperature  were  all  made  with 
healthy  people,  including  five  men  and  one  woman;  the  data  regarding  the 
age,  height,  and  weight  of  these  subjects  may  be  found  in  table  6.  With  but 
few  interruptions,  the  experiments  continued  daily  from  the  beginning  of  Janu- 
ary until  the  middle  of  March,  1911.  The  experimental  conditions  remained 
essentially  the  same  throughout  the  series,  save  that  in  all  experiments  prior  to 
January  27,  1911,  the  water  in  the  Dewar  flask  inside  of  the  constant-tempera- 
ture oven  was  not  stirred  by  compressed 
air.  While  this  change  in  the  apparatus 
tended  to  insure  a  constancy  of  temperature 
that  added  somewhat  to  the  accuracy  of 
the  subsequent  results,  nevertheless  the 
experiments  were  usually  of  short  duration, 
and  hence  were  not  subject  to  wide  errors 
due  to  imperfect  stirring. 

Previous  to  an  experiment,  the  ther- 
mometers were  adjusted  and  the  subject 
immediately  lay  down  on  a  comfortable 
couch  or  occasionally  sat  in  a  chair,  chang- 
ing the  position  from  time  to  time  to  avoid 

extreme  discomfort.  In  each  experiment  one  main  question  was  usually 
studied,  and  incidentally  numerous  minor  points.  In  giving  the  results, 
therefore,  it  seems  best  to  present  the  curves  for  each  experiment  by  itself, 
with  the  conclusions  drawn  therefrom,  and  finally  to  summarize  the  results  and 
give  the  conclusions  drawn  from  the  experiments  as  a  whole.  In  these  curves, 
as  usual,  the  time  is  expressed  by  distance  measured  horizontally  and  temper- 
ature is  represented  vertically.  The  records  for  the  various  localities  are 
designated  as  follows:  Deep  rectum,  RD;  shallow  rectum,  Rgj  deep  vagina, 
VD;  shallow  vagina,  V8;  right  axilla,  AH;  left  axilla,  AL;  mouth,  M;  groin,  G; 
upper  leg,  L;  hand,  Hc  and  HF;  and  various  surface  points,  S. 

EXPERIMENTAL   RESULTS. 

Experiment  of  January  6,  1911,  with  (7.  H.  H. — A  thermometer  was  placed 
in  each  axilla,  and  two  thermometers  in  the  rectum,  one  of  the  latter  being 
inserted  10.4  centimeters,  and  the  other  6  centimeters.  The  experiment 
began  shortly  after  the  subject  reached  the  laboratory  in  the  morning,  and  it 
will  be  noticed  that  in  consequence  there  was  an  initial  fall  in  temperature  of 
both  the  rectal  thermometers.  This  is  usual  after  muscular  exercise,  even  so 


Subject. 

Age. 

Height. 

Weight 
without 
clothing. 

years. 

cm. 

kilo. 

Mrs.  B—  1.. 

43 

164 

56 

F.  G.  B... 

40 

183 

83 

J.  J.   C... 

27 

175 

65 

C.  H.  H.. 

18 

169 

55 

V.  G  

17 

162 

55 

F.  A.  R... 

34 

163 

74 

46 


TEMPERATURE   FLUCTUATIONS   IN    THE   HUMAN    BODY. 


limited  an  amount  of  exercise  as  would  be  incidental  to  coming  to  the  labora- 
tory. The  length  of  time  required  to  raise  the  temperature  in  the  axilla  to 
constancy  was  from  20  to  30  minutes;  when  constancy  had  been  assured,  the 
axillas  were  opened  and  cooled  for  a  short  time,  and  the  thermometers  again 
inserted. 

The  two  axillas  had  about  the  same  temperature  curve,  and  in  a  general  way 
the  fluctuations  followed  those  in  the  rectum;  the  records  of  the  axilla  ther- 
mometers were,  however,  lower  than  those  of  either  the  shallow  or  the  deep 
rectal  thermometer. 

The  results  of  the  measurements  are  shown  in  fig.  15,  in  which  the  curves 
are  marked  as  previously  indicated. 


8.30A.M.  8.50        9.10         9.30        9.50       10.10          10.30      10.50 
FIG.  15.  Temperature  curves  for  experiment  of  January  6,  1911,  with  C.  H.  H. 

Experiment  of  January  6, 1911,  with  Mrs.  B—  I.— This  experiment  was  made 
primarily  to  test  the  feasibility  of  obtaining  the  body-temperature  of  women. 
The  subject  came  to  the  laboratory  after  the  noon  meal  and  immediately  lay 
down  upon  the  couch.  A  single  thermometer  was  inserted  in  the  rectum  to 
a  depth  of  7  centimeters  and  a  second  thermometer  in  the  vagina.  A  ther- 
mometer was  also  placed  in  the  right  axilla,  the  subject  lying  on  the  same  side 
to  keep  the  cavity  closed.  No  special  bandages  were  used.  In  addition,  a 
fourth  thermometer  was  placed  under  the  breast,  with  the  breast  folded  over 
it  as  much  as  possible  and  kept  in  place  by  a  bandage.  At  4h  23m  p.  m.,  the 
thermometer  was  removed  from  under  the  breast  and  placed  in  the  groin;  the 
axilla  was  also  opened  at  this  time,  and  the  thermometer  replaced  in  the  cavity 
at  4h  34m  p.  m.  The  curves  for  the  rectum  and  the  vagina  had  agreed  remark- 
ably well  until  this  time,  but  during  the  change  the  vaginal  thermometer  was 
accidentally  moved  out  of  position  and  the  temperature  record  changed  to  a 
level  a  little  over  0.5°  C.  below  the  original.  After  the  vaginal  thermometer 


DISCUSSION   OF  RESULTS. 


47 


had  slipped  out,  it  was  unquestionably  more  or  less  covered  by  the  labia  and 
the  fleshy  portion  of  the  leg,  so  that  the  temperature  was  not  extremely  low. 
The  subject  lay  in  a  somewhat  curled-up  position  after  the  placing  of  the  ther- 
mometer in  the  groin,  which  helped  to  keep  the  record  of  the  vaginal  ther- 
mometer high  in  spite  of  the  fact  that  it  was  not  deeply  inserted. 

An  unusually  long  time  was  required  for  the  thermometers  in  the  artificial 
cavities  to  reach  constancy,  this  being  unquestionably  due  to  the  imperfect 
closing  of  the  cavities.  The  curves  for  these  localities  follow  each  other  quite 
closely,  but  illustrate  admirably  the  difficulty  of  securing  proper  temperature 
records  without  special  precautions  for  perfect  closure. 


37. 4°C 

372 

37.0 

36.8 

36.6 


3.20  RM.  2.40        3JOO         3.20        3.40       4>OO        4.20         4.4O         5.00        570 
FIG.  16.  Temperature  curves  for  experiment  of  January  6.  1911,  with  Mrs.  B— 1. 

The  results  of  the  temperature  measurements  are  given  in  fig.  16.  The 
curves  for  the  rectal  and  axilla  thermometers  are  marked  in  the  usual  way, 
while  the  curve  for  the  vagina  is  designated  as  V,  that  for  the  thermometer 
placed  under  the  breast  as  S,  and  for  the  thermometer  in  the  groin  as  G. 

Experiment  of  January  7, 1911,  with  J.J.C. — Both  the  deep  and  the  shallow 
thermometers  were  used  in  the  rectum,  inserted  to  a  depth  of  10  centimeters 
and  5  centimeters  respectively.  Temperature  records  were  also  taken  simul- 
taneously in  both  axillas,  the  arms  being  folded  across  the  chest  and  held  in 
place  by  cloth  bandages  so  as  to  insure  perfect  closure.  The  subject  sat  in  a 
chair  during  the  experiment  and  was  very  sleepy.  At  12h  09m  p.  m.,  both 
axilla  thermometers  were  removed  so  as  to  give  more  freedom  of  movement. 
Between  12h  16m  p.  m.  and  12h  36m  p.  m.  the  subject  ate  a  dinner  consisting 


48 


TEMPERATURE    FLUCTUATIONS   IN   THE    HUMAN    BODY. 


of  steak,  rolls,  and  coffee.  At  12h  57m  p.  m.  he  changed  to  a  more  comfortable 
lounging  chair  and  the  axilla  thermometers  were  replaced.  At  lh  35m  p.  m. 
he  put  his  feet  up  on  another  chair. 

The  occasional  fluctuations  noted  in  the  curve  for  the  shallow  rectal  ther- 
mometer were  probably  due  to  the  fact  that  the  thermometer  was  not  inserted 
to  a  sufficient  depth,  as  the  observer  noted  that  the  temperature  fluctuated 


DISCUSSION   OF  RESULTS. 


whenever  the  subject  moved  his  legs.  Of  particular  interest,  however,  is  the 
fact  that  while  the  curve  for  the  shallow  rectal  thermometer  is  much  lower 
than  that  for  the  deeper  thermometer,  the  two  curves  follow  each  other  very 
closely,  thus  indicating  simultaneously  the  temperature  gradient  previously 
discussed,  and  also  a  constancy  in  the  curve  of  body-temperature  at  different 
parts  of  the  body.  The  temperature  curves  for  the  axillas  show,  first,  the 
long  time  required  to  warm  the  axilla  to  constancy,  and  second,  the  fact  that 
unless  special  precautions  are  taken  to  hold  the  thermometers  in  place  and 
fully  covered  with  flesh,  the  results  will  have  but  little  value.  There  is  a 
marked  lack  of  uniformity  between  the  temperature  curves  for  the  axillas 
and  that  for  the  rectal  thermometer.  This  can  be  explained  only  by  the  fact 
that  the  subject  was  very  sleepy  and  proper  precautions  were  not  taken  to 


37.2 
37.0 
36.8 
36.6 


•V 


A 


2.30PM.  2.40        3.00        3.20        3.4O        4.00        4.20        4.4O          5.00        5.20 
?.  ;.  H  .      Temperature  curves  for  experiment  of  January  9,  1911,  with  Mrs.  B — 1. 

insure  a  thorough  closure  of  both  axillas,  although  it  is  a  significant  fact  that 
both  the  axilla  temperature  curves  show  a  tendency  to  fall  off  at  about  the 
same  degree  of  rapidity. 

The  results  of  the  temperature  measurements  are  given  in  fig.  17,  the  curves 
being  designated  in  the  usual  manner. 

Experiment  of  January  9,  1911,  -with  Mrs.  B—l.—A  single  thermometer  was 
used  in  the  rectum  and  another  in  the  vagina,  each  being  inserted  to  a  depth 
of  7  centimeters.  A  thermometer  was  also  used  in  each  of  the  axillas  and  one 
between  the  breasts,  which  were  drawn  together  and  folded  over  the  ther- 
mometer by  means  of  a  cloth  belt.  The  thermometers  in  the  artificial  cavities 
required  a  long  time  to  reach  constancy,  doubtless  on  account  of  the  imperfect 
closure  of  the  cavities.  At  3h  30m  p.  m.  both  the  thermometer  in  the  right 


50 


TEMPERATURE    FLUCTUATIONS   IN    THE    HUMAN    BODY. 


axilla  and  the  skin  thermometer  were  removed;  also,  the  rectal  thermometer 
and  the  vaginal  thermometer  were  each  supposedly  withdrawn  2  centimeters. 
At  this  time,  however,  the  vaginal  thermometer  slipped  out,  causing  a  discrep- 
ancy in  the  records.  At  4h  09m  p.  m.  both  the  rectal  thermometer  and  the 
vaginal  thermometer  wrere  returned  to  their  original  positions,  without  disturb- 
ing the  left  axilla,  and  from  this  time  on  the  curves  agree  very  satisfactorily. 

The  results  of  the  temperature  measurements  are  given  in  fig.  18,  the  curves 
being  marked  as  usual. 

Experiment  of  January  11,  1911,  with  J.  J.  C. — This  experiment  was  divided 
into  three  parts  in  order  to  study  the  rectal  gradient,  the  effect  of  warming  the 
axilla  previous  to  inserting  the  thermometer  also  being  studied.  Two  ther- 
mometers were  used  in  the  rectum,  and  one  in  each  axilla.  In  the  first  part  of 
the  experiment,  the  deep  thermometer  was  inserted  in  the  rectum  to  the  depth 
of  7  centimeters,  and  the  shallow  thermometer  to  the  depth  of  4  centimeters;  in 
the  second  part,  the  insertions  were  5.5  centimeters  and  2.5  centimeters  respec- 
tively; and  in  the  last  part,  3.75  centimeters  and  0.75  centimeter. 


37.  at 


36.8 


'a.20RM.Z.40        3.00         3.20         3.40        4.00 


4.20         4.40 


Fia.  19.  Temperature  curves  for  experiment  of  January  11,  1911,  with  J.  J.  C. 

Previous  to  the  first  part  of  the  experiment,  a  hot-water  bottle,  at  a  tempera- 
ture of  40°  C.,  was  placed  in  the  left  axilla  for  5  minutes,  the  thermometer 
being  inserted  in  the  right  axilla,  as  usual  without  preheating.  The  effect  of 
this  preheating  is  shown  by  the  fact  that  the  curve  for  the  left  axilla  rose  more 
abruptly  than  that  for  the  right.  In  the  second  part  of  the  experiment,  the 
conditions  were  reversed,  a  hot-water  bottle  with  a  temperature  of  45°  C. 
being  used  in  the  right  axilla,  but  none  in  the  left.  Without  doubt  the  tempera- 
ture of  the  water  used  was  too  high,  as  the  curve  for  the  right  axilla  did  not 
fall  to  the  temperature  level  of  the  body  for  some  time.  In  the  third  part  of 
the  experiment,  the  conditions  of  the  first  part  were  duplicated,  the  hot- 
water  bottle  at  a  temperature  of  40°  C.  being  placed  in  the  left  axilla,  and  the 
thermometer  inserted  in  the  right  axilla  without  preheating  the  cavity.  The 
same  tendency  to  an  abrupt  rise  in  the  curve  for  the  left  axilla  was  again  noted, 
although  it  was  not  so  pronounced  as  in  the  first  part  of  the  experiment.  The 
curves  for  the  rectal  thermometers  show  the  usual  fall  in  temperature  at  the 
beginning  of  the  experiment.  It  should  be  noted  that  the  curves  for  the  deep 


DISCUSSION    OF   RESULTS. 


5J 


and  shallow  rectal  temperatures,  by  being  roughly  parallel  but  not  coincident, 
indicate  clearly  the  thermal  gradient  already  discussed  in  considerable  detail.1 
In  view  of  this  fact  and  that  previous  experiments  indicate  a  similar  gradient, 
a  fall  in  temperature  would  be  expected  to  follow  the  withdrawal  of  the  ther- 
mometers to  a  less  depth.  This  fall  in  temperature  is  not,  however,  shown. 
The  discrepancy  can  be  explained  only  by  the  fact  that  as  the  thermometers 
were  adjusted  by  the  subject,  which  involved  considerable  movement  on  his 
part,  the  statement  regarding  the  depths  of  insertion  is  doubtless  inaccurate. 

The  measurements  of  the  body-temperature  in  the  different  localities  are 
given  in  fig.  19,  the  curves  being  designated  as  usual. 

Experiment  of  January  12,  1911,  with  C.  H.  H. — The  deep  and  shallow 
rectal  thermometers  were  used,  also  a  thermometer  in  each  axilla,  the  axillary 
thermometers  being  held  in  place  by  bandages.  This  experiment,  like  the 
preceding,  was  divided  into  three  parts  so  that  a  study  could  be  made  of  the 
rectal  gradient  and  of  the  effect  of  preheating  the  axilla.  In  the  first  part  of 
the  experiment,  the  depth  of  insertion  of  the  shallow  thermometer  was  6.5 
centimeters,  and  of  the  deeper  thermometer,  9.5  centimeters;  in  the  second 
part,  they  were  inserted  4  and  7  centimeters,  respectively;  and  in  the  third 
part,  0.75  centimeter  and  3.75  centimeters,  respectively.  A  ho-twater  bottle, 
at  a  temperature  of  40°  C.,  was  placed  in  the  left  axilla  5  minutes  before  the 
experiment  commenced,  the  right  axilla  not  being  preheated.  In  the  second 
part  of  the  experiment,  the  left  axilla  was  again  preheated  by  means  of  a  hot- 
water  bottle  at  the  same  temperature  as  before,  while  in  the  last  part  the 
hot-water  bottle,  at  a  temperature  of  42.5°  C.,  was  used  in  the  right  axilla. 

During  the  experiment,  the  subject  apparently  slept  at  times,  but  usually 
was  lying  awake  and  quiet.  In  the  first  part  of  the  experiment,  the  left  axilla 
had  a  temperature  somewhat  above  that  of  the  right,  although  the  records  for 
the  two  thermometers  remained  parallel  after  constancy  had  been  obtained. 


37.0°C 


8.30A.M.    8.50         9.10         9.30         9.50          10.10          IO-3O       10.50         11.10         H.30          11.50       IZ.IOP.M.  12.30 
FIG.  20.  Temperature  curves  for  experiment  of  January  12,  1911,  with  C.  H.  H. 

At  the  beginning  of  the  second  part,  the  temperature  curve  for  the  left  axilla 
was  above  normal,  but  fell  rapidly  until  the  two  axillary  curves  became  essen- 
tially the  same.  In  the  third  part  of  the  experiment,  the  preheating  of  the 

'See  p.  35. 


52 


TEMPERATURE  FLUCTUATIONS   IN   THE  HUMAN   BODY. 


right  axilla  raised  the  temperature  above  normal  and  consequently  this  curve 
shows  an  initial  fall,  while  the  curve  for  the  left  axilla  rose  as  usual,  becoming 
constant  in  approximately  20  minutes. 

It  is  noted  that  here,  as  in  the  preceding  experiment,  the  rectal  temperature 
curves  are  apparently  unaffected  by  a  change  in  the  depth  of  insertion.  The 
explanation  is  probably  the  same  as  before,  namely,  that  the  depth  of  insertion 
was  changed  by  the  subject  himself,  and  therefore  the  depths  as  stated  may  be 
very  seriously  questioned.  The  fluctuations  in  both  the  rectal  curves  follow 
each  other  with  considerable  regularity,  the  curves  being  in  general  parallel. 

The  measurements  of  the  body-temperature  are  given  in  fig.  20,  the  designa- 
tions of  the  curves  being  as  usual. 

Experiment  of  January  12,  1911,  with  F.  A,  R. — In  this  experiment  a  single 
thermometer  was  used  in  the  rectum  at  a  depth  of  10.5  centimeters;  also, 
two  thermometers  were  placed  between  the  hands,  one  in  the  center  of 
the  palms,  the  other  near  the  base 
of  the  second  finger.  To  provide  for 
the  closure  for  the  two  latter  ther- 
mometers, the  hands  were  firmly 
clasped  and  tied  together  with 
bandages.  The  curves  for  the 
hands  show  at  first  the  slowness  of 
the  cavity  in  approaching  its  final 
temperature;  then,  beginning  about 
2h  30m  p.  m.,  there  was  a  decided  fall 
in  temperature,  undoubtedly  caused 
by  the  unconscious  partial  opening 
of  the  hands.  The  strain  upon  the 
wrists  was  relieved  at  2h  46m  p.  m. 
by  fastening  a  cotton  strap  about 
the  arms  above  the  elbows  to  prevent 
the  hands  from  opening;  after  this 
the  cavity  gradually  increased  in 
temperature,  the  curves  following 
essentially  the  same  course.  It  re- 
quired a  long  time  for  the  cavity 
to  attain  body-temperature,  and  as 
the  subject  appeared  to  be  uncom- 
fortable, the  experiment  was  discon- 
tinued before  any  opportunity  was 
afforded  to  observe  the  parallelism 
of  the  three  curves. 

The  measurements  of  the  body- temperature  are  given  in  fig.  21,  the  designa- 
tion for  the  rectal  curve  being  the  same  as  usual,  those  for  the  hands  being  Hc 
and  H,  for  the  thermometers  in  the  center  of  the  palms  and  at  the  base  of  the 
second  finger,  respectively. 


37.8 
376 
374 
37.2 
37.0 
36.8 
36.6 
36.4 
36.2 
36.0 
35.8 

\ 

\ 

^ 

\ 

X 

X 

*^*^ 

•-»-»- 

?t* 

i:i 

He, 

A  A 

^ 
A* 

A 

A            t 

HFA 

A 

*A 

A' 

A* 

A 

z 

A 

I.4OP.M.   2.00         2.20        240         3.00          3.20      3.4< 
Fio.  21.  Temperature  curves  for  experiment  of  January 
12,  1911,  with  F.  A.  R. 


DISCUSSION   OF  RESULTS.  53 

Experiment  of  January  13,  1911,  with  V.  G— In  this  experiment,  a  ther- 
mometer was  used  in  the  rectum  at  a  depth  of  9.5  centimeters;  also,  as  in  the 
previous  experiment,  a  thermometer  was  placed  in  the  center  of  the  palms  and 
another  at  the  base  of  the  second  finger,  with  the  hands  clasped  and  tied  with 
bandages.  The  space  between  the  hands  was  warmed  for  5  minutes  before 
the  experiment  by  a  hot-water  bottle  at  a  temperature  of  40°  C. 

During  the  experiment  the  subject  occasionally  fell  asleep,  but  sat  quietly 
the  remainder  of  the  time.  The  two  thermometers  in  the  hand  gave  readings 
which  agree  very  well  with  each  other,  and  while  the  parallelism  with  the 
records  of  the  rectal  thermometer  is  not  perfect,  there  was  a  tendency  for  the 
temperature  of  the  hand  to  fall  as  the  temperature  in  the  rectum  fell.  The 
slight  rise  between  3h  19m  p.  m.  and  3h  41m  p.  m.  indicated  by  the  curve  for 
the  rectal  thermometer  is  also  seen  in  the  curves  for  the  thermometers  in  the 
hand. 

The  measurements  for  this  experiment  may  be  found  represented  in  fig.  22, 
with  the  designations  of  the  curves  as  for  previous  experiments. 


v, 


** 


1.40P.M.      2.00         2.20         2.40         3.00          3.20         3.40        4.00         4.20        4.40 
Fio.  22.  Temperature  curves  for  experiment  of  January  13,  1911,  with  V.  G. 

Experiment  of  January  14,  1911,  with  C.  H.  H. — In  this  experiment  the 
subject  sat  in  the  chair,  and  both  the  deep  and  the  shallow  rectal  thermometers 
were  used,  the  former  inserted  to  the  depth  of  9.5  centimeters,  and  the  latter 
6  centimeters.  The  temperature  of  the  hands  was  taken  by  two  thermome- 
ters as  in  previous  experiments,  the  hands  being  clasped  and  bandaged  as 
usual.  Still  another  thermometer  was  placed  between  the  crossed  legs  above 
the  knees.  No  hot-water  bottle  was  used. 

The  initial  fall  in  the  rectal  temperature,  noted  in  practically  all  of  the 
experiments,  is  here  very  well  marked.  The  curves  representing  the  tempera- 
ture in  the  hands  remained  fairly  parallel  throughout,  but  did  not  follow  the 
curve  of  the  rectal  thermometer.  On  the  other  hand,  the  temperature  of 
the  upper  leg,  while  requiring  a  very  long  time  to  reach  equilibrium,  followed 
the  rectal  temperature  with  remarkable  constancy  and  accuracy  when  it  had 
finally  reached  the  upper  level.  An  effort  was  made  in  other  experiments  to 
measure  the  body-temperature  between  the  crossed  legs,  but  these  attempts 


54 


TEMPERATURE    FLUCTUATfONS   IN    THE   HUMAN   BODY. 


were  unsuccessful,  and  the  locality  does  not  appear  favorable  for  such  observa- 
tions, as  its  use  involves  much  discomfort  to  the  subject. 

The  records  obtained  in  this  experiment  are  given  in  fig.  23,  the  curves  being 
designated  as  usual,  that  for  the  artificial  cavity  between  the  crossed  legs 
being  marked  L. 


37.4°C 


Hc 


**! 


I.IOPM.  1.30          1.50        3.10         230        2.50        310         3.30         3.50        4.10        4.30 
Fio.  23.  Temperature  curves  for  experiment  of  January  14,  1911,  with  C.  H.  H. 

Experiment  of  January  16,  1911,  with  Mrs.  B — 1. — The  deep  and  shallow 
thermometers  were  used  in  the  rectum,  inserted  7.5  centimeters  and  4  centi- 
meters respectively,  and  a  single  thermometer  in  the  vagina  at  a  depth  of 


37.6°C 


^< 
/      Sr       X 


230PM  Z50        3.10         330        3.50        4.10         4.30         4.50         5.10 
FIG.  24.  Temperature  curves  for  experiment  of  January  16,  1911,  with  Mrs.  B— 1. 

10  centimeters.  A  thermometer  was  also  placed  in  the  left  groin.  At  the 
beginning  of  the  experiment  a  thermometer  was  strapped  between  the  arm 
and  the  breast,  but  the  temperature  for  this  locality  was  very  slow  in  reaching 


DISCUSSION    OF   RESULTS.  55 

constancy  and  the  thermometer  was  later  removed,  and  two  thermometers 
were  placed  side  by  side  in  the  left  groin. 

The  usual  initial  fall  in  temperature  on  lying  down  on  the  couch  is  well 
shown  in  the  curves  for  the  deep  and  shallow  rectal  thermometers  and  for  the 
vaginal  thermometer.  The  temperatures  for  these  three  localities  followed 
one  another  with  fair  constancy  throughout  the  whole  test.  The  groin  tem- 
perature required  considerable  time  to  reach  constancy,  but  thereafter  followed 
the  fluctuations  in  the  temperature  of  the  rectum  and  the  vagina  with  reason- 
able regularity.  As  will  be  seen  by  the  curves,  the  thermometers  used  in  the 
latter  part  of  the  experiment  for  obtaining  the  temperature  of  the  groin  agreed 
fairly  well  with  each  other,  and  also  followed  closely  those  of  the  rectum  and  the 
vagina.  While  the  temperature  indicated  by  the  shallow  rectal  curve  is 
considerably  lower  than  that  of  the  deep  rectal  curve,  it  is  interesting  to  note 
that  the  parallelism  of  the  two  records  is  very  marked. 

The  records  for  this  experiment  are  given  in  fig.  24;  the  curves  are  designated 
in  the  usual  manner,  the  curve  for  the  thermometer  between  the  arm  and  the 
breast  being  marked  S,  and  those  for  the  groin,  Gi  and  G2. 

Experiment  of  January  17, 1911,  with  Mrs.  B — 1. — In  view  of  the  parallelism 
shown  in  the  previous  experiment  between  the  groin  temperature  and  the 
temperatures  of  the  rectum  and  the  vagina,  this  experiment  was  designed  to 


37.  8  C 

\ 

^ 

%> 

\!**S 

o 

M^ 

>^* 

^*u 

^ 

-" 

O 

x  

^—  - 

* 

370 

2.20PM.   2.4O          3.00          3.20          3.40         4,00        4.20         4AO          5.00         5.20 
FIG.  25.  Temperature  curves  for  experiment  of  January  17,  1911,  with  Mrs.  B— 1. 

make  a  comparative  study  of  the  temperatures  of  the  groin,  the  deep  and  the 
shallow  vagina,  and  the  rectum,  a  thermometer  being  placed  in  all  of  these 
localities.  In  the  rectum,  the  thermometer  was  inserted  to  a  depth  of  7 
centimeters,  while  in  the  vagina,  one  thermometer  was  inserted  to  the  depth 
of  10  centimeters,  and  the  other  to  the  depth  of  6.5  centimeters.  Before 
the  experiment  began,  a  hot-water  bottle  at  a  temperature  of  42°  to  43°  C. 
was  placed  in  the  groin  for  5  minutes.  From  the  curves,  it  may  be  seen  that 
the  groin  temperature  was  at  first  considerably  higher  than  normal,  then 
fell  off  until  it  reached  a  constant  level  somewhat  below  that  of  the  vagina  and 
the  rectum,  and  thereafter  followed  in  a  general  way  the  fluctuations  of  the 
other  thermometers. 

The  records  of  the  experiment  may  be  found  in  fig.  25,  with  the  curves 
designated  as  usual. 


56 


TEMPERATURE   FLUCTUATIONS   IN   THE    HUMAN   BODY. 


Experiment  of  January  20,  1911,  with  C.  H.  H.—In  this  experiment  the 
subject  crossed  his  arms  on  his  chest,  and  one  thermometer  was  placed  between 
the  lower  arm  and  the  chest,  and  another  at  the  point  where  the  arms  crossed. 
In  addition,  two  thermometers  were  used  in  the  rectum,  and  one  in  each  of 
the  axillas,  6  thermometers  in  all  being  used.  The  thermal  junctions  were 
kept  in  position  in  the  usual  way  by  bandages.  The  locations  between  the 
crossed  arms,  and  between  the  arm  and  the  chest  are  particularly  unfavorable 
for  accurate  records  of  body-temperature,  as  it  is  difficult  to  secure  a  perfect 

closure.  The  curves,  however,  seem 
to  follow  one  another  very  fairly, 
this  doubtless  being  due  to  the  care 
exercised  by  the  subject  not  to  dis- 
place the  thermometers.  No  hot- 
water  bottles  were  used  for  preheat- 
ing any  of  the  cavities,  and  conse- 
quently the  length  of  time  required 
for  the  different  parts  to  reach  equi- 
librium is  very  well  shown  by  the 
rise  in  the  temperature  curve  at  the 
beginning  of  the  experiment.  The 
usual  initial  fall  of  the  deep  and  the 
shallow  rectal  temperatures  is  shown 
in  this  experiment.  Between  3h  17m 
p.  m.  and  3h  22m  p.  m.,  the  legs  were 
uncovered  in  an  attempt  to  produce 
a  lowering  of  the  temperature  by 
exposing  the  skin  surface,  but  this 
was  without  appreciable  effect. 

The  records  of  the  measurements 

are  given  in  fig.  26,  the  curves  being  marked  as  usual.  The  curve  for  the 
thermometer  between  the  arm  and  the  chest  is  designated  by  Si  and  the  curve 
for  the  thermometer  at  the  point  where  the  arms  crossed  by  82. 

Experiment  of  January  23,  1911,  with  C.  H.  H. — In  this  experiment  the 
deep  and  shallow  rectal  thermometers  were  used  to  give  a  base  line  for  com- 
parison with  the  records  of  thermometers  inserted  in  the  right  and  the  left 
axillas  between  the  crossed  arms,  as  in  the  previous  experiment,  and  in  the 
mouth.  The  thermometers  in  the  rectum  were  inserted  12  centimeters  and 
8.5  centimeters  respectively.  The  subject  lay  on  a  couch  on  his  right  side, 
the  thermometers  in  the  axillas  being  held  in  position  by  bandages  as  usual. 
At  10h08m  a.m.,  the  subject  became  uncomfortable,  and  lay  on  his  back 
instead  of  on  his  right  side.  Between  10h22m  a.m.  and  10h27m  a. m.,  the  legs 
were  uncovered  to  find  if  exposure  would  lower  the  temperature.  As  a  matter 
of  fact,  the  curves  indicate  a  slight  rise  in  temperature  instead  of  a  fall.  The 
temperature  in  the  left  axilla  quite  closely  parallels  that  in  both  the  rectum 
and  the  mouth.  The  abnormal  course  of  the  temperature  in  the  right  axilla 


2.00PM    2.20        3.40 


3.20        3.40       4.00 


FIG.  26.  Temperature  curves  (or  experiment  of  Jan.  20, 1911, 
with  C.  H.  H.;  3.17p.  m.  to  3.22p.m.,  body  surf  ace  exposed. 


DISCUSSION    OF   RESULTS. 


57 


and  between  the  arms  can  be  readily  explained  by  the  difficulty  in  securing  a 
proper  position  on  account  of  the  discomfort  of  the  subject.  It  is  of  interest 
to  note  that  from  10h  20m  a.m.  to  11  a.m.,  the  temperature  between  the  arms 
(curve  M)  followed  almost  exactly  that  of  the  rectum. 

The  records  of  the  measurement  may  be  found  in  fig.  27,  the  designations  of 
the  rectal  and  axillary  curves  being  as  usual.  The  curves  for  the  thermometers 
between  the  crossed  arms  and  in  the  mouth  are  marked  S  and  M,  respectively. 


8.50A.M.  9.10          9.30        9.50         10.10        10.30       10.50       11.10 

FIG.  27.  Temperature  curves  for  experiment  of  January  23,  1911,  with  C.  H.  H.; 
10.22  a.  m.  to  10.27  a.  m.,  body  surface  exposed. 

Experiment  of  January  24, 1911,  with  J.  J.  C. — The  conditions  of  this  experi- 
ment were  essentially  the  same  as  in  the  experiment  of  January  23,  save  that 
a  different  subject  was  chosen  and  the  thermometer  between  the  arms  was 
omitted.  Two  thermometers  in  the  rectum  were  used  at  a  depth  of  8  centi- 
meters and  4.5  centimeters,  respectively,  one  in  each  of  the  axillas,  and  one  in 
the  mouth.  The  subject  slept  much  of  the  time  during  the  experiment,  and 
there  was  consequently  so  much  trouble  in  securing  a  proper  closure  of  the 
mouth  that  at  9h31m  a.  m.  the  mouth  thermometer  was  removed  and  replaced 
at  9h44ra  a.m.  surgeon's  plaster  being  used  to  hold  the  lips  together.  At 
9h46m  a.m.,  the  subject  changed  his  position  and  lay  more  on  his  side.  Be- 
tween 10h59m  a.  m.  and  Ilh03m  a.m.,  he  drank  1\  cupfuls  of  hot  coffee,  the 
thermometers  in  the  mouth  and  the  axillas  being  removed  for  this  purpose. 
The  subject  then  turned  on  his  side  and  the  thermometer  was  replaced  in  the 
left  axilla.  The  thermometer  in  the  mouth  was  likewise  replaced,  surgeon's 
plaster  being  again  applied.  Near  the  end  of  the  experiment,  there  were 
indications  that  the  shallow  rectal  thermometer  was  closer  to  the  anus  than 
was  reported  by  the  subject;  the  wide  discrepancies  between  the  records  of 


58 


TEMPERATURE   FLUCTUATIONS    IN   THE    HUMAN    BODY. 


the  two  rectal  thermometers  from  Ilh10m  a.m.  to  Ilh59m  a.m.  can  hardly  be 
explained  in  any  other  way.  Similarly,  at  the  beginning  of  the  experiment  a 
temperature  difference  of  approximately  0.6°  C.  between  the  two  rectal  records 
appears  to  be  due  to  the  fact  that  the  shallow  rectal  thermometer  was  not 
inserted  to  so  great  a  depth  as  was  supposed. 

The  measurements  of  the  temperature  are  shown  in  fig.  28,  the  curves  being 
marked  as  in  previous  experiments. 


,.    8.30A.M.  8.50        9.10          930         950         10.10        10.30       1050         11.10         "30        H.50      IZ.IORM. 
FIG.  28.  Temperature  curves  for  experiment  of  January  24,1911,  with  J.  J.  C.;  10.59a.m.  to  11.03  a.m. 
drinking  hot  coffee. 

Experiment  of  January  27,  1911,  with  Mrs.  B—l. — In  this  and  all  succeed- 
ing experiments,  compressed  air  was  used  to  stir  the  water  in  the  Dewar  flask 
in  the  constant-temperature  oven. 

Two  thermometers  were  used  in  the  vagina,  at  a  depth  of  10  and  6.5  centi- 
meters, respectively,  and  a  thermometer  in  the  rectum  at  a  depth  of  6  centi- 
meters. In  addition,  a  thermometer  was  placed  in  the  groin  and  one  in  the 
right  axilla,  and  intermittent  observations  were  made  in  the  mouth. 

The  curves  for  this  experiment  are  interesting  in  that  they  show  a  period 
of  3  hours  in  which  the  temperature  in  the  vagina  and  the  rectum  did  not 
change  more  than  approximately  0.1°  C.  The  deep  and  shallow  thermometers 
in  the  vagina  remained  within  0.07°  C.  of  each  other  throughout  the  whole  test, 
the  records  with  the  deep  vagina  thermometer  being  somewhat  higher  than 
those  with  the  shallow  thermometer.  The  rectal  temperature  was  slightly 
higher  than  the  vaginal  temperature,  the  maximum  deviation  from  the  tem- 
perature of  the  deep  vagina  being  0.07°  C.  It  was  observed  that  during  this 
experiment  the  rectal  thermometer  was  embedded  in  feces.  The  thermometer 
in  the  groin  required  about  20  minutes  to  reach  constancy.  The  curves  for 
both  the  axilla  and  the  groin  temperatures  follow  in  a  general  way  the  parallel 
temperatures  of  the  deeper  thermometers,  although  the  temperature  fluctua- 


DISCUSSION    OF   RESULTS. 


59 


tions  throughout  the  whole  test  were  not  sufficiently  striking  to  make  these 
records  of  very  great  value  in  this  connection.  The  records  of  the  mouth 
temperature  are  chiefly  of  interest  as  indicating  the  time  required  to  warm  the 
cavity  to  approximate  constancy.  With  the  mouth  closed  about  10  minutes 
prior  to  taking  the  temperature  (see  the  curve  at  about  4h29m  p.m.),  constancy 
was  reached  in  about  8  minutes.  With  the  mouth  open  for  10  minutes  pre- 
vious to  taking  the  temperature,  a  period  of  over  15  minutes  was  required 
(see  the  curve  at  about  5  p.m.). 

The  records  of  body-temperature  may  be  found  in  fig.  29,  the  curves  being 
designated  as  usual. 


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FIG.  29.  Temperature  curves  for  experiment  of  January  27,  1911,  with  Mre.  B— 1. 

Experiment  of  January  31,  1911,  with  Mrs.  B — L — In  this  experiment  the 
temperature  was  taken  in  the  vagina  with  the  deep  and  the  shallow  ther- 
mometers; in  the  rectum  with  a  single  thermometer,  also  in  the  groin,  and  in 
either  the  right  or  the  left  axilla,  no  hot-water  bottle  being  used  for  preheat- 
ing the  artificial  cavities.  An  attempt  was  also  made  to  secure  the  temperature 
of  the  mouth  from  time  to  time  throughout  the  day,  the  subject  being  asked 
not  to  breathe  through  the  mouth  previous  to  the  observations. 

At  the  beginning  of  the  experiment,  the  thermometer  in  the  right  axilla 
was  not  in  proper  position,  and  it  was  accordingly  readjusted  at  9h58m  a.  m. 
When  this  temperature  had  attained  the  maximum,  however,  it  remained 
fairly  constant.  At  Ilh58m  a.m.  the  subject  changed  from  the  couch  to  a 
chair,  and  sat  quietly  reading,  except  between  lh  04m  p.m.  and  lh  29m  p.m., 
when  she  ate  a  dinner  consisting  of  steak,  coffee,  and  potato  chips.  At  3h  25m 
p.m.  she  lay  down  again  on  the  couch  and  remained  either  sleeping  or  lying 
quietly  awake  for  the  rest  of  the  experiment.  During  the  time  she  sat  in  the 
chair,  the  thermometer  was  placed  in  the  left  axilla,  and  that  in  the  groin 
removed.  When  she  again  lay  down  on  the  couch,  however,  the  thermometers 
were  returned  to  their  original  positions. 

The  curves  for  the  deep  and  the  shallow  vaginal  temperatures  and  for  the 
rectal  temperature  follow  one  another  throughout  the  day  with  remarkable 
regularity  for  the  most  part.  The  groin  temperature  required  a  long  time  to 
reach  the  maximum,  but  thereafter  the  records  followed  those  for  the  rectum 


60  TEMPERATURE    FLUCTUATIONS   IN    THE   HUMAN    BODY. 

and  the  vagina.  On  changing  the  thermometer  to  the  left  axilla,  considerable 
time  was  required  for  the  temperature  to  reach  the  maximum,  and  this  was 
also  the  case  when  the  right  axilla  was  again  used  after  the  subject  lay  down 
on  the  couch  in  the  afternoon.  The  records  of  mouth  temperature  are  of 
value  only  for  showing  the  length  of  time  required  to  reach  the  maximum; 
the  highest  point  in  the  curve  should  be  taken  to  indicate  the  actual  temper- 
ature of  the  mouth,  an  imaginary  curve  joining  these  high  points  conforming 
to  the  general  shape  of  the  curves  for  the  deep  thermometers.  The  tendency 
for  the  curves  to  rise  throughout  the  day,  even  when  the  subject  lay  on  the 
couch,  is  characteristic  of  the  diurnal  variation  in  which  the  highest  temper- 
ature is  in  the  late  afternoon.  « 

The  curves  showing  the  body-temperature  for  the  different  localities  may  be 
found  in  fig.  30. 

Experiment  of  February  3,  1911,  with  Mrs.  B — L — The  deep  and  shallow 
vaginal  thermometers  were  used  in  this  experiment,  inserted  to  a  depth  of  10 
and  6.5  centimeters,  respectively,  also  a  single  rectal  thermometer  at  a  depth 
of  8  centimeters.  Thermometers  were  placed  in  the  groin,  in  either  the  right 
or  left  axilla,  and  temperatures  were  taken  intermittently  in  the  mouth 
throughout  the  experiment.  A  hot-water  bottle  at  a  temperature  of  44°  C. 
was  used  in  the  axilla,  and  another  with  a  temperature  of  49°  G.  in  the  groin 
for  about  5  minutes  before  the  experiment,  but  this  preheating  was  not  so 
effective  as  usual  in  shortening  the  time  required  to  secure  constancy. 

During  the  first  part  of  the  experiment  the  subject  lay  on  the  couch  quietly 
reading.  At  9h  19m  a.  m.  the  axilla  thermometer  was  placed  in  a  better  posi- 
tion, and  later  (at  llh  24m  a.  m.),  as  the  subject  had  been  moving  about  con- 
siderably, it  was  again  readjusted.  At  12h  14m  p.  m.,  the  subject  changed  from 
the  couch  to  the  chair;  at  the  same  time  the  thermometer  was  changed  from 
the  right  axilla  to  the  left  axilla,  which  had  been  previously  heated  by  means  of 
a  hot-water  bottle  at  a  temperature  of  46.5°  C.  The  temperature  of  the  left 
axilla  fell  for  the  first  few  minutes,  indicating  that  the  preheating  had  raised 
the  temperature  of  the  cavity  somewhat  above  the  normal.  From  1 h  Olm  p.  m. 
to  lh  25m  p.  m.  the  subject  was  eating  dinner.  At  2h  30m  p.  m.  she  lay  down 
on  the  couch  again,  a  hot-water  bottle  at  a  temperature  of  47°  C.  being  placed 
in  the  groin,  and  another  at  the  same  temperature  in  the  axilla.  In  both 
instances  the  temperature  rose  considerably,  but  apparently  the  maximum  tem- 
perature was  reached  in  a  much  shorter  time  than  in  the  earlier  portion  of  the 
test.  At  3h  Olm  p.  m.,  the  lips  were  fastened  together  with  surgeon's  plaster 
in  order  to  keep  the  mouth  thermometer  in  place  for  continuous  observation. 
The  subject  was  asleep  and  moved  about  somewhat.  At  4h  24m  p.  m.  she  was 
asked  to  keep  the  mouth  tightly  closed.  Finally  the  thermometer  was  removed 
from  the  mouth  at  4h  56m  p.  m.  and  reinserted  without  the  use  of  plaster  at 
5h  19m  p.  m.  A  higher  temperature  was  then  observed  in  this  locality,  which 
may  have  been  due  to  a  better  closure  of  the  mouth  after  the  rest  in  the  interval 
when  the  thermometer  was  not  in  position. 

The  peculiar  feature  of  the  curves  in  this  experiment  is  the  general  uniformity 
of  the  records  for  the  deep  and  the  shallow  vaginal  thermometers  and  the  rectal 


DISCUSSION   OF  RESULTS. 


01 


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2  i 


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62  TEMPERATURE   FLUCTUATIONS   IN   THE   HUMAN    BODY. 

thermometer,  with  the  single  exception  of  the  record  for  the  shallow  vaginal 
thermometer  between  2  p.  m.  and  2h  30ra  p.  m.  It  would  appear  as  if  the 
thermometers  in  the  vagina  had  been  displaced  during  this  interval,  and  that 
the  shallow  thermometer  had  slipped  out  of  the  cavity.  The  groin  tempera- 
ture followed  with  considerable  regularity  the  temperature  indicated  by  the 
other  thermometers,  while  the  inequalities  of  the  axillary  temperature  in  the 
early  part  of  the  experiment  may  be  accounted  for  by  the  restless  movements 
of  the  subject.  The  great  irregularities  in  the  temperature  of  the  mouth 
accentuate  the  undesirability  of  this  locality  for  such  observations. 

The  curves  showing  the  records  of  body-temperature  may  be  found  in  fig.  31. 

Experiment  of  February  6-7,  1911,  with  Mrs.  B — 1. — This  experiment  was 
planned  to  continue  for  24  hours,  in  order  to  secure  the  total  diurnal  variation. 
The  subject  was  lying  on  a  couch  during  the  whole  experiment  except  when 
sitting  in  a  chair  between  llh  59m  a.  m.  and  2h  10m  p.  m.,  and  5h  24m  p.  m. 
and  1 1 h  19m  p.  m.  A  single  thermometer  was  inserted  in  the  rectum  at  a  depth 
of  8  centimeters,  and  both  deep  and  shallow  thermometers  in  the  vagina  at  a 
depth  of  10  centimeters  and  6.5  centimeters  respectively.  While  the  sub- 
ject lay  on  the  couch,  temperature  observations  were  made  in  the  right  axilla 
and  in  the  groin.  During  the  time  the  subject  sat  in  the  chair,  the  groin  obser- 
vations were  discontinued,  and  the  axillary  temperature  was  taken  in  the  left 
axilla  instead  of  the  right.  Observations  of  the  mouth  temperature  were  made 
intermittently. 

At  the  beginning  of  the  experiment  the  groin  and  axilla  were  warmed  by 
means  of  hot-water  bottles  at  a  temperature  of  45°  C.  The  temperature  of 
the  groin  reached  the  maximum  very  shortly,  but  the  temperature  of  the  axilla 
required  a  long  time  to  acquire  constancy.  An  abnormal  and  wholly  inexplica- 
ble rise  in  axillary  temperature  was  noted,  beginning  at  10h  39m  a.  m.  When 
the  subject  changed  from  the  couch  to  the  chair  at  llh  59m  a.  m.,the  groin  tem- 
perature records  were  discontinued  and  the  temperature  was  taken  in  the  left 
axilla  instead  of  the  right,  so  that  the  subject  could  use  the  right  hand  in  eating. 
Before  inserting  the  thermometer,  the  left  axilla  was  heated  with  a  hot-water 
bottle,  at  a  temperature  of  47°  C.,  but  gave  very  unsatisfactory  results  at  first. 
The  subject  was  asked  to  readjust  the  thermometer  at  12h  59m  p.  m.,  and  the 
results  thereafter  were  much  more  uniform.  Between  lh  07in  p.  m.  and  lh  32m 
p.  m.  she  ate  her  dinner,  and  at  2h  12m  p.  m.,  she  returned  to  the  couch.  The 
groin  and  axilla  were  heated  with  hot-water  bottles  at  a  temperature  of  47°  C. 
before  the  thermometers  were  inserted,  and  the  temperature  of  the  groin  rose 
considerably  above  even  that  of  the  rectum,  cooling  again  rapidly  to  a  constant 
temperature.  The  axillary  temperature  also  quickly  attained  constancy.  The 
subject  was  asleep  between  3h  17m  p.  m.  and  4h  07m  p.  m.,  and  on  waking  up 
asked  for  water,  drinking  a  half  glassful  at  4h  12m  p.  m.  While  it  may  have 
been  a  mere  coincidence,  all  of  the  curves  show  a  slight  tendency  to  a  lowering 
of  the  temperature  after  the  drinking  of  the  cold  water.  At  5h  24m  p.  m.  the 
subject  again  changed  from  the  couch  to  the  chair,  and  the  axillary  temperature 
was  taken  in  the  left  axilla,  while  the  groin  records  were  discontinued.  During 


DISCUSSION    OF   RESULTS. 


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64  TEMPERATURE    FLUCTUATIONS   IN    THE    HUMAN    BODY. 

this  period,  the  subject  ate  her  supper.  While  she  sat  in  the  chair,  the  records 
were  so  irregular  that  they  are  not  given.  It  is  possible  that  the  thermometers 
were  not  well  located,  as  it  was  noted  that  a  difference  in  temperature  was 
caused  by  the  subject  sitting  forward  or  back  in  the  chair.  At  11 h  19™  p.  m. 
the  subject  changed  from  the  chair  to  the  bed,  and  beginning  at  llh  45m  p.  m. 
the  temperature  curves  are  again  given.  The  groin  and  right  axilla  were  heated 
by  means  of  a  hot- water  bottle  at  a  temperature  of  47°  C.  The  groin  tem- 
perature was  noticeably  affected  by  the  preheating  and  rapidly  attained  con- 
stancy, but  the  temperature  in  the  right  axilla  required  the  usual  20  minutes 
to  reach  a  constant  level.  The  subject  lay  very  quietly  the  first  of  the  night, 
and  the  temperature  curves  fell  off  in  accordance  with  the  general  diurnal  varia- 
tion. From  lh  30m  a.  m.  to  2  a.  m.  she  moved  about  considerably,  and  also 
between  3  a.  m.  and  3h  27m  a.  m.  At  3h  27m  a.  m.  the  subject  was  told  that 
she  need  not  keep  the  groin  closed,  and  this  temperature  record  was  discon- 
tinued until  4h  12m  a.  m.  She  reported  that  she  had  slept  at  times.  The 
subject  moved  more  or  less  until  about  5  o'clock,  but  she  was  very  quiet  from 
5  a.  m.  until  5h  30m  a.  m.  Later  she  moved  somewhat  and  at  6h  46m  a.  m. 
asked  several  questions.  The  groin  and  axilla  thermometers  were  removed  at 
7h  14m  a.  m.,  and  the  deep  and  the  shallow  vaginal  thermometers  at  7h  52m 
a.  m.  At  8  a.  m.  the  thermometer  was  replaced  in  the  groin,  the  groin  and 
rectal  temperatures  being  recorded  continuously  thereafter.  The  subject  ate 
breakfast  between  8h15m  a.  m.  and8h39m  a.  m.,  and  from  that  time  until  theend 
of  the  experiment,  at  9h  27m  a.  m.,  she  was  awake,  talking  and  reading. 

While  the  groin  required  considerable  time  to  reach  a  constant  temperature, 
except  when  preheated,  when  the  body-temperature  had  finally  been  acquired 
the  records  followed  with  remarkable  regularity  those  for  the  rectum  and  the 
vagina.  The  temperature  of  the  axilla  varied  considerably  and  does  not  show 
the  parallelism  which  would  be  expected,  this  parallelism  evidently  depending 
upon  the  accuracy  and  constancy  with  which  the  axilla  is  closed,  thus  accentu- 
ating very  sharply  the  fact  that  the  groin  is  on  the  whole  a  much  better  locality 
than  the  axilla  for  taking  body-temperatures.  The  temperature  observations 
made  in  the  mouth  show  their  usual  irregularity,  although  a  curve  drawn 
through  the  maximal  readings  would  follow  the  curves  for  the  rectum  and  the 
vagina. 

The  curves  showing  the  records  of  body-temperature  may  be  found  in  fig.  32. 

Experiment  of  February  27,  1911,  with  J.  J.  C. — In  this  experiment  the  deep 
and  shallow  thermometers  were  used  in  the  rectum  at  depths  of  9.5  and  6 
centimeters  respectively,  and  a  thermometer  in  the  left  axilla.  A  ther- 
mometer was  also  inserted  in  the  mouth  and  held  there  continuously. 

During  the  experiment  the  subject  sat  in  a  chair,  sometimes  awake  and 
reading  and  sometimes  apparently  asleep.  At  9h  23m  a.  m.  he  drank  some 
cold  water.  He  changed  his  position  in  the  chair  at  10h  33m  a.  m.,  and  the 
axilla  thermometer  was  also  readjusted  at  this  time.  At  llh  16m  a.  m.  the 
left  shoulder  became  uncovered,  and  at  llh  22m  a.  m.  the  subject  removed 
his  feet  from  the  couch  on  which  he  had  been  resting  them.  From  12h  2Jm 


FIG.  32.  Temperature  curves  for  experiment 
of  February  6-7,  1911,  with  Mrs.  B-l. 
1  07  p.  m.  to  1.32  p.  m.,  eating;  4.12 
p.  m.,  drinking  water;  8. 15  a.  m.  to  8.39 
a.  m.,  eating. 


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66 


TEMPERATURE    FLUCTUATIONS    IN    THE    HUMAN    BODY. 


p.  m.  to  12h  38m  p.  m.  he  was  eating,  the  thermometers  in  the  mouth  and  in 
the  axilla  being  removed  during  this  time.  Before  reinserting  the  thermometer 
in  the  left  axilla,  the  cavity  was  heated  by  a  hot-water  bottle  at  a  temperature 


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of  40°  C.;  this  resulted  in  a  rapid  rise  to  constancy.  Toward  the  end  of  the 
experiment  the  subject  became  very  tired  and  uncomfortable,  and  at  2h  14m 
p.  m.  rested  his  feet  on  the  couch  again. 


DISCUSSION   OF  RESULTS. 


67 


The  general  tendency  toward  parallelism  of  all  of  these  curves  is  rather 
striking;  nevertheless,  the  temperature  of  the  mouth  exhibits  considerable 
fluctuation  from  time  to  time, 
and  the  temperature  of  the  left 
axilla  falls  off  more  rapidly  be- 
tween llh  18m  a.  m.  and  llh  48m 
a.  m.  than  do  either  the  deep  or 
the  shallow  rectal  temperatures, 
these  differences  being  more 
marked  than  in  most  of  the  ex- 
periments. The  rapidity  with 
which  the  temperature  of  the 
left  axilla  came  to  constancy  after 
the  use  of  the  hot-water  bottle  at 
12h  47m  p.  m.  is  also  noticeable. 

The  measurements  of  the  body- 
temperature  are  shown  in  fig.  33. 

Experiment  of  March  1,  1911, 
with  C.  H.  #.— The  deep  and 
shallow  rectal  thermometers  were 
used  in  this  experiment,  with  an 
insertion  of  12  and  8.5  centimeters, 
respectively.  A  thermometer  was 
also  used  in  the  left  axilla,  and 
one  in  the  mouth.  This  experi- 
ment was  designed  to  duplicate 
more  or  less  the  experimental  con- 
ditions of  the  study  made  with 
J.  J.  C.  on  February  27.  The 
mouth  temperature  was  not  taken 
continuously,  however.  A  hot- 
water  bottle  at  a  temperature  of 
43°  C.  was  used  in  the  left  axilla. 
The  subject  was  eating  between 
12h  37m  p.  m.  and  lh  04m  p.  m.; 
at  lh  05m  p.  m.  he  changed  the 
position  of  his  feet,  resting  them 
on  a  stool  instead  of  on  the  couch. 

The  parallelism  of  the  curves  is 
very  striking  in  all  instances,  the 
curve  for  the  axilla,  although 
showing  a  lower  temperature,  fol- 
lowing the  curves  for  the  rectal  Oo 
temperature  very  satisfactorily,  ft  £  £  $  m  n  « 

The  measurements  of  the  body-temperature  may  be  found  in  fig.  34. 


TEMPERATURE    FLUCTUATIONS   IN   THE   HUMAN   BODY. 


Experiment  of  March  2,  1911,  with  F.  A.  R. — The  deep  and  shallow  rectal 
thermometers  were  used,  with  an  insertion  of  12  centimeters  and  8.5  centi- 
meters respectively,  and  two  thermometers  in  the  hand,  one  in  the  center  of 
the  palms  and  one  at  the  base  of  the  second  finger,  the  cavity  between  the 
hands  having  been  previously  heated  with  a  hot-water  bottle  at  a  temperature 
of  42°  C.  Intermittent  observations  were  also  made  of  the  mouth  tempera- 
ture. As  in  previous  experiments,  the  hands  were  closely  clasped,  tied  with 
cloth  bandages,  and  covered  with  a  pile  of  loose  pieces  of  cloth.  The  arms 
were  bound  together  above  the  elbows,  as  usual,  to  prevent  the  spreading 
apart  of  the  wrists.  At  8h  58m  a.  m.  one  of  the  hand  thermal  junctions  was 
inserted  a  little  farther  toward  the  center  of  the  hand.  To  test  the  effect  of 
hot  and  cold  drinks,  the  subject  was  given  cold  water  at  9h  48m  a.  m.  and  a 
cupful  of  hot  coffee  at  llh  08m  a.  m. 

37.6°C| 


36.8 
36.6 
36A 


36.2 


,jtf 


8.30A.M.  8.50        9.10 


9.30        9.50 


10.30       10.50 


FIG.  35.  Temperature  curves  for  experiment  of  March  2.  1911,  with  F.  A.  R.    9.48  a.  m.,  drinking 
cold  water;  11.08  a.  m.,  drinking  hot  coffee. 

In  a  general  way  the  curve  for  the  thermometer  in  the  middle  of  the  hand 
follows  the  curve  for  the  rectal  thermometer,  although  in  the  latter  part  of  the 
experiment  the  rise  in  temperature  is  not  so  noticeable  as  in  the  curve  for  the 
rectal  thermometer.  While  the  temperature  curve  for  the  thermometer  at 
the  base  of  the  second  finger  shows  wide  variations,  nevertheless  the  general 
tendency  is  not  far  from  that  shown  in  the  curve  for  the  thermometer  in  the 
middle  of  the  palms.  The  temperatures  taken  in  the  mouth  are  very  irregular 
and  it  is  impossible  to  draw  any  deductions  from  the  observations  in  this  cavity. 
Just  after  taking  hot  coffee,  a  slight  rise  may  be  noted  in  all  of  the  temperature 
curves,  but  the  cold  water  appeared  to  have  no  effect. 

The  curves  showing  the  measurement  of  the  body-temperature  may  be 
found  in  fig.  35. 

Experiment  of  March  3,  1911,  with  F.  G.  B. — In  this  experiment,  the  shallow 
and  deep  rectal  thermometers  were  used,  a  thermometer  in  the  left  axilla, 
and  one  in  the  mouth.  Before  inserting  the  thermometer  in  the  left  axilla, 


DISCUSSION   OF  RESULTS.  69 

the  cavity  was  heated  by  means  of  a  hot-water  bottle  at  42°  C.  The  subject 
sat  in  a  chair  throughout  the  experiment.  From  2h  55m  p.  m.  until  3h  23m 
p.m.,  he  endeavored  by  muscular  activity  to  stimulate  a  rise  in  temperature; 
he  moved  his  legs  and  arms  and  exercised  with  a  stool,  lifting  it,  holding  it  at 
arm's  length,  and  raising  and  lowering  it  above  the  head.  He  also  placed  a 
book  rest  on  his  toes,  and  moved  it  up  and  down.  The  exercise  was  sufficient 
to  cause  perspiration  and  fatigue.  After  the  exercise,  he  was  very  quiet, 
closed  his  eyes,  and  tried  to  go  to  sleep.  His  elbows  rested  on  the  arms  of  the 
chair,  and  his  head  on  his  hands.  At  3h  41m  p.  m.,  as  the  mouth  thermometer 
was  in  position,  some  directions  were  written  on  a  piece  of  paper.  At  3h  49m 
p.  m.,  400  cubic  centimeters  of  cold  water  at  a  temperature  of  4.8°  C.  were  taken. 
During  the  muscular  work,  the  mouth  thermometer  was  used,  and  held 
continuously  in  place  until  it  was  removed  when  the  cold  water  was  taken. 
It  was  then  immediately  replaced  and  allowed  to  come  to  the  maximum 
temperature. 


1.40  RM.    Z.OO 


3.00        3.20         3.40       4.00        4.20       4.4O 


Fio.  36.  Temperature  curves  for  experiment  of  March  3, 1911,  with  F.  G.  B.    2.55  p.  m.  to  3.23  p.  m., 
muscular  exercises;  3.49p.  m.,  drinking  cold  water. 

Special  care  was  exercised  by  the  subject  to  keep  the  mouth  closed  and  to 
breathe  only  through  the  nose,  so  as  to  keep  the  mouth  temperature  as  nearly 
constant  as  possible.  Care  was  also  taken  not  to  disturb  the  position  of  the 
axillary  thermometer.  The  curves  for  this  experiment  show  remarkably 
well  the  uniformity  between  the  deep  and  the  shallow  rectal  temperatures, 
the  temperature  in  the  left  axilla,  and  that  in  the  mouth.  The  fluctuations 
during  the  muscular  exercise,  the  succeeding  quiet  condition,  and  the  taking 
of  the  cold  water  were  almost  exactly  equal  in  all  the  curves  and  were  clearly 
defined.  As  would  be  expected,  the  muscular  exercise  produced  a  rise  in 
temperature,  while  the  subsequent  quiet  condition  and  the  taking  of  cold 
water  evidently  caused  a  lowering  of  the  temperature. 

The  curves  showing  the  body-temperature  measurements  for  the  different 
localities  may  be  found  in  fig.  36. 


70 


TEMPERATURE   FLUCTUATIONS   IN   THE   HUMAN    BODY. 


Experiment  of  March  10,  1911,  with  J.  J.  C—  The  deep  and  the  shallow 
rectal  thermometers  were  used  at  a  depth  of  15  centimeters  and  11.5  centi- 
meters, respectively.  A  thermometer  was  also  placed  in  the  left  axilla,  this 
cavity  having  been  previously  heated  by  a  hot-water  bottle  at  a  temperature 
of  42.5°  C.,  and  intermittent  observations  were  also  taken  in  the  mouth.  The 
influence  of  muscular  activity  was  studied  in  this  experiment,  and  beginning 
at  3h  26m  p.  m.  the  subject  exercised  quite  vigorously.  This  activity  appeared 
to  tire  him,  as  he  breathed  heavily  and  perspired  freely.  During  the  exercise 
he  was  more  or  less  exposed,  as  he  wore  a  blanket  over  his  shoulders  instead 
of  a  sweater.  At  3h  49m  p.  m.  he  stopped  exercising  and  became  quiet.  For 


37.6 
37.4- 
37. 2 
37.0 
36.8 
36.6 
36.4- 


I\ 


2.IORM.  3.30        2.50 


3.30        3.50       4.10 


4-.30        4-.50 


Fio.  37.  Temperature  curves  for  experiment  of  March  10, 1911,  with  J.  J.  C.    3.26  p.  m.  to  3.49  p.  m., 
muscular  exercise. 

some  unaccountable  reason  there  was  not  a  very  close  parallelism  between 
the  two  rectal  records,  although  all  of  the  curves  show  a  general  tendency 
toward  parallelism,  especially  the  curves  of  the  rectal  and  the  axillary  temper- 
atures. The  muscular  exercise  did  not  produce  a  rise  in  the  temperature; 
while  this  is  not  easy  to  explain,  it  may  have  been  due  to  the  fact  that  the 
surface  of  the  skin  was  more  exposed  during  the  exercise  than  when  the  sub- 
ject was  quiet,  causing  a  tendency  to  cool  the  surface. 

The  curves  showing  the  measurements  of  the  body-temperature  in  the 
different  localities  may  be  found  in  fig.  37. 

Experiment  of  March  13,  1911,  with  F.  A,  R. — In  this  experiment  both  deep 
and  shallow  rectal  temperatures  were  taken,  also  the  temperature  of  the  left 


DISCUSSION   OF   RESULTS. 


71 


axilla,  and  occasionally  the  temperature  of  the  mouth.  The  two  rectal  ther- 
mometers were  inserted  at  a  depth  of  10  and  6.5  centimeters  respectively. 
The  axilla  was  preheated  by  means  of  a  hot-water  bottle  at  a  temperature  of 
42° C.,  which  caused  the  subject  to  perspire;  during  the  experiment  the  bandage 
holding  the  axilla  thermometer  loosened.  In  previous  experiments  it  had 
been  noted  that  the  rectal  temperatures  usually  fell  at  the  beginning  of  an 
experiment,  which  would  indicate  that  the  temperature  when  the  subject  was 
active  before  the  experiment  was  higher  than  after  he  became  quiet.  For 
this  reason  it  was  decided  to  take  the  mouth  temperature  at  the  very  beginning 
of  the  experiment.  If  the  curves  indicating  the  mouth  and  rectal  temperatures 


Z.IO         Z.30        a.50         3.10         3.30 


FIG.  38.  Temperature  curves  for  experiment  of  March  13, 1911,  with  F.  A.  R.    3.02  p.  m.  to  about  3.50 
p.m.,  muscular  exercise ;  3. 50  p.  m.,  drinking  cold  water. 

are  to  be  parallel,  this  first  observation  of  the  mouth  temperature  should  be 
very  high,  and  this  was  found  to  be  actually  the  case.  At  3h02m  p.m.,  the 
subject  began  to  exercise  by  lifting  a  stool,  and  at  3h32m  p.m.  he  was  still 
exercising  but  networking  very  hard.  At  3h50mp.  m.,  just  after  he  had 
stopped  exercising,  he  drank  a  glass  of  cold  water  at  a  temperature  of  10°  C. 
A  subsequent  fall  in  temperature  of  almost  0.2°  C.  was  noted,  which  may  have 
been  due  in  part  to  the  influence  of  the  cold  water.  The  temperature  curves 
for  this  experiment  were  in  general  parallel,  the  curves  for  the  temperatures 
of  the  mouth  and  the  rectum  being  more  nearly  parallel  than  usual. 

The  curves  showing  the  measurement  of  the  body-temperature  in  the 
different  localities  may  be  found  in  fig.  38. 


72          'i  EMPERATURE  FLUCTUATIONS  IN  THE  HUMAN  BODY. 


CONCLUSIONS. 

From  this  series  of  temperature  observations  made  on  a  number  of  different 
subjects,  certain  definite  conclusions  have  been  drawn: 

1.  When  two  thermc  meters  are  placed  in  one  internal  cavity  at  not  less  than 
6  centimeters  deep,  the  temperature  curves  are  parallel  and  approximately 
equal.     This  is  shown  in  figs.  15,  20,  23,  25,  27,  29,  30,  31,  32,  33,  34,  35,  36, 
and  38,  but  certain  abnormalities  not  easily  explainable  are  seen  in  figs.  26 
and  37. 

2.  When  two  thermometers  are  placed  in  one  internal  cavity  and  the  dis- 
tance between  them  is  3.5  centimeters,  one  being  within  5  centimeters  of  the 
surface  of  the  body,  the  curves  obtained  are  parallel,  but  not  equal  in  value, 
thus  indicating  a  temperature  gradient.     See  figs.  17,  19,  24,  and  28. 

3.  Thermometers  placed  in  the  rectum  and  the  vagina,  at  depths  of  at 
least  6  centimeters,  show  curves  that  are  parallel  and  approximately  equal. 
See  figs.  16,  18,  24,  25,  29,  30,  31,  and  32. 

4.  Thermometers  in  the  right  and  left  axillas  give  curves  that  are  parallel, 
showing  approximately  equal  temperatures.     This  is  indicated  in  figs.  15,  17, 
and  a  part  of  19,  also  in  20  and  26.     Exceptions  to  this  are  shown  in  figs.  18, 
27,  and  28,  but  in  considering  these  exceptions  one  must  not  lose  sight  of  the  fact 
that  it  is  very  difficult  to  secure  constant  and  well-closed  axillas  undisturbed 
by  body  movements;  we  have  every  reason  to  believe  that  the  conflicting 
results  in  these  three  curves  are  due  to  misplaced  thermometers. 

5.  Two  thermometers  placed  in  the  groin  give  results  that  are  parallel  and 
approximately  equal.     This  is  shown  in  fig.  24. 

6.  Two  thermometers  placed  in  the  hand  give  results  that  are  equal  and 
parallel.     See  figs.  21,  22,  and  23.     In  fig.  35,  the  curves  are  parallel  but  not 
equal,  indicating  a  slight  gradient. 

7.  The  use  of  the  hot-water  bottle  hastens  the  warming-up  of  such  artificial 
cavities  in  the  body  as  the  axilla,  groin,  and  hand.     This  fact  is  shown  in  figs. 
19,  20,  and  22,  and  in  parts  of  31,  32,  and  33,  also  in  34,  35,  36,  37,  and  38. 

8.  When  lying  on  a  couch  after  the  slight  muscular  work  involved  in  coming 
to  the  laboratory  and  moving  about  before  the  experiment,  there  is  usually  an 
initial  fall  of  internal  temperature.     This  is  clearly  evident  in  figs.  15,  19,  20, 
21,  22,  23,  24,  26,  27,  28,  33,  34,  36,  and  37,  but  not  so  well  shown  in  figs.  17, 
18,  25,  29,  30,  and  35,  and  is  entirely  absent  in  figs.  16,  31,  32,  and  38. 

9.  Temperatures  taken  in  the  mouth  are  in  general  extremely  irregular  and 
unsatisfactory,  as  may  be  seen  in  figs.  28,  29,  30,  part  of  31,  and  32,  also  in 
fig.  35.     Nevertheless  fair  results  are  shown  in  figs.  27,  33,  and  34,  and  very 
satisfactory  results  in  figs.  36  and  38. 

10.  The  effect  of  eating  a  meal  tends  to  increase  somewhat  the  temperature 
of  the  body.     See  figs.  17,  30,  31,  32,  33,  and  34. 

11.  On  exposing  portions  of  the  skin  under  the  conditions  of  the  experiments 
here  made,  no  effect  on  body-temperature  was  apparent  in  figs.  26  and  27. 


DISCUSSION    OF   RESULTS.  73 

12.  On  drinking  hot  coffee,  the  body  temperature  was  very  slightly  in- 
creased.    This  is  shown  in  figs.  28  and  35. 

13.  Drinking  cold  water  had  a  tendency  to  lower  the  body-temperature. 
See  figs.  36  and  38.     This  effect  was  not  evident  in  the  experiment  repre- 
sented by  fig.  35,  however. 

14.  Muscular  exercise  produced  a  marked  increase  in  body-temperature 
in  at  least  one  experiment  (see  fig.  36),  but  was  without  effect  in  others  (see 
figs.  37  and  38).     Of  significance  was  the  fact  that  while  obtaining  the  data 
for  fig.  37,  the  skin  of  the  subject  was  more  or  less  exposed  to  the  air. 

15.  The  internal  temperature  of  the  body  and  that  of  the  axilla,  breast, 
groin,  hand,  arm,  and  mouth,  have  a  tendency  toward  parallelism.     This  is 
evident  in  practically  all  of  the  curves,  but  is  especially  well  shown  for  the 
internal  temperature  and  the  axilla  in  figs.  20,  27,  33,  34,  36,  and  38,  although 
in  fig.  27  this  is  not  true  of  the  right  axilla  for  reasons  previously  explained. 
The  parallelism  is  also  shown  for  the  internal  temperature  and  the  groin  in 
figs.  24,  25,  and  31;  for  the  internal  temperature  and  the  mouth  in  figs.  27,  33, 
34,  36,  and  38;  and  for  the  internal  temperature  and  the  upper  leg  in  fig.  23. 

Finally,  it  can  be  stated  that  an  examination  of  all  the  results  obtained 
shows  in  the  temperature  curves  a  remarkable  trend  toward  parallelism,  a 
parallelism  that  would  be  exact,  there  is  every  reason  to  believe,  if  the  ther- 
mometers could  remain  in  precisely  the  same  position  and  if  the  cavities 
could  remain  absolutely  constant  in  their  closure.  We  feel  justified,  there- 
fore, in  summing  up  this  work  by  stating  that,  aside  from  the  skin  temperature, 
a  rise  or  fall  in  rectal  temperature  is  accompanied  by  a  corresponding  rise  or 
fall  in  temperature  of  all  other  parts  of  the  body. 

NUTRITION  LABORATORY,  CARNEGIE  INSTITUTION  OF  WASHINGTON, 

Boston,  Massachusetts,  July,  1911, 


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